Is the 'Acceptance of Resignation' letter legally binding?

Hi Sirs, I joined a private company a year before and was working in the (email support) customer service team. My performance has been one of the best in this period. In an effort to downsize the workforce the company decided to let go of a certain percentage of the workforce and the managers/ team leads were assigned the task of choosing gullible scapegoats. The ploy was to transfer the employees (read demote) to a lower department knowing fully well that no employee with an iota of self respect will accept the same and would rather leave than to accept such kind of ignobility. Some of the managers did what they would naturally do and put in the names of the people in the list whom they had any sort of issue with and not based on performance or stats of the employee or any such criterion which could be justifiable in the least. In the list was my name as well and in an effort by the company to save on the severance package the chosen were taken to a meeting and told that this so called transfer (read demotion) is because of our exemplary performance (no pun intended because the management/ manager really did say that this is being done because of our good performance and he could not be blamed because if he had said due to poor performance, there was available the performance stats which would have immediately proven him wrong). The inevitable happened and every one resigned and were told to serve a months notice period. To inform you of the 10 or so people in my batch 3 were senior employees including me. We had been directly recruited to the department and the recruitment had happened on the understanding that we are joining the before mentioned department (we joined only after knowing the job description and under no circumstance would we have joined if they had recruited us to this lower department). This was a kind of salt on the wound situation for three of us. All three of us had one thing in common that we had escalated one or more of the team lead's / manager's misdoings to higher management and Out of the three of us one employee directly blurted out against his manager at the workplace and security was summoned and this employee who had served in the organisation for many years was promptly escorted out. The other one went on the floor and threatened suicide and said so will do his family as he is the only support to them. Immediately there came the police DCP and legal adviser to the company who outranks every one in the particular branch. This employee had demanded compensation (read severance package) and an apology from the team lead who had included his name in the list. The legal adviser promptly advised the employee to not commit suicide as it is illegal and said that he seeks his apology for any misdoings. This employee was provided exemption from serving notice period and about two months of salary as compensation and his full and and final settlement was done with company providing him 'Acceptance of Resignation' letter immediately and 'Relieve letter' due in 45 days as per the procedure. Me being the decent and gullible person that I am, accepted to serve the 30 day notice period but not before much deliberation with the management. One thing that I could not let go of is my leave balance as they said that during the notice period leaves will not be provided and company does not have a leave encashment policy. You see while I was working leave grants was entirely up to the discretion of the reporting manager and my leave request had been denied an unjustifiable number of times because of which there was a big pile up of my leave balance. After they realized that I will never accept this last injustice, they relented and told the privilege leave balance will be adjusted in the notice period but there was caveat included that I can take only privilege leave but not comp/ offs which I also had a balance. The arrangement was that as I was forced to resign on the 5th of month resulting in my last working day as 4th of the next month. I was told to work till 23rd and take leave for the next 10 days (though I had more than 10 leave balance) and just come and collect my 'Acceptance of resignation' letter on 4th of next month and my full and final settlement will be processed along with my relieve letter in 45 days time after that. However after working for 13 days and 10 more days being left for my notice period apart from the granted leaves, I received a urgent call informing that my father who is a diabetic is in a serious condition. I immediately consulted my team lead on the floor and appraised him of the situation and left for my native with his consent and as he was aware of my situation he told me to not worry and attend to my father and he will make sure that I will not be required to work for these 10 days but I will still get what I had been promised. I did not find the need to send email as I trusted him that he will not tell me wrong in that circumstance. I was really thankful to him when I found the softcopy of the 'Acceptance of Resignation' letter with my last working day dated as 4th of the month as agreed and signed by the H.R director on my email ID later on. It was informed that my full and final settlement along with the relieve letter will be processed as per the procedure in 45 days and I was advised to submit any company property that I had with me. As my father's health had improved I returned to Bengaluru on 12th day and visited the company H.R two days later just to return my company ID card which I still had with me. This was the same H.R person who was a part of all those ploys which I had informed you about earlier. Once I met the HR I was aghast to hear that as per her understanding, I am an absconder and hence there was a argument as she was not ready to hear any thing otherwise from me and was talking to me with a condescending and dictatorial behavior. Finally I showed her the print out of the 'Acceptance of Resignation' which I had received. Now she seemed to be perplexed (not sure if it was genuine perplexity or made up) and I requested her to clarify on the same as I also had attended an interview with another company just a day prior and had been selected and also had submitted all my educational and service documents including this 'Acceptance of Resignation' letter. She asked me to leave and asked to get in touch via email about this issue. Then I tried calling my team lead to whom I had informed about my leaves and he did not receive my calls after multiple attempts and has not answered any of my calls so far and quite frankly I have started to doubt his intentions. On the very same day that I met her, I emailed the H.R lady and the Exit HR team seeking clarification. The reply I got was shell shock to me as it said that I should disregard the 'Acceptance of Resignation' letter sent to me earlier and they are going to process me as absconder now and will provide a different service letter with a different last working day than what had been mentioned and no relieve letter. It was also mentioned that there will be deduction from my full and final settlement accordingly. A clause on the offer letter with regard to termination was cited in the email to support this injustice. (In case you need to look at this clause please reply so that I can scan this clause on my offer letter and attach the same here). I have become speechless at the enormity of this injustice and dictatorial behavior and seeking help in this regard.I hope you understand my dilemma as they are still feeding me to the wolves in spite of me doing almost everything they asked. Getting new job is not easy and I have got a very good offer from another company and have also submitted this 'Acceptance of Resignation' letter as supporting document. My questions are. 1) Is the 'Acceptance of Resignation' letter issued on the company letterhead and signed by the H.R director binding as per law or can the company withdraw the same unilaterally as per their wish and whim? 2) What options do I have in either case if the answer to the above question is YES or NO. 3) What options will I have in case this company denies my experience to the next company during verification. Dear Sirs please reply and help me. Thanks.