1. Whichever seperation clause added now to harass you can be quashed and you need not follow/ are not bound to obey it, since it was not mentioned in your appointment order.

2. Management/HR can't unilaterally insert a clause now and for which you have not agreed so far and it's an afterthought by the HR/Management to harass you so that your relieving can be indefinitely postponed.

3. If there's buy out option clause in your appointment order, the HR is bound to honour your request for buying out the whole/shortfall notice period.

Legally, the  modification is not enforceable against you, being not part of offer letter. But legal remedies take time. Even if you approach Court against the  subsequent modification of terms of resignation, it will not rake less than one year. Settle the  dispute amicably with HR without getting in to legal tangle. Legal proceedings will also spoil you name in market.

Serve the extended notice period .

obtain relieving letter and experience certificate from your employer 

The clauses inserted by the management subsequent to your acceptance of the employment is not maintainable until and unless you have accepted the new terms. 

An universal decision introduced by the management regarding employment terms and conditions is against the law in force.

You can issue a legal notice to the company about this and demand relieving you on the date of last working day and to deduct from your F & F settlement if at all any amount to be compensated towards the non observance of the notice period. 

If there's buy out option clause in your appointment order, the HR is bound to honour your request for buying out the whole/shortfall notice period.

Dear client I'm sorry to hear that but in this case you can file a complaint against the manager or HR to your Organisation head or you can file a case of harassment against him before your  nearest police station.

It is better for you to serve out the notice period as required by your HRD, as otherwise they may harass you unnecessarily by delaying your relieving letter, experience certificate etc., besides eligible monetary benefits.

- As per Specific Relief Act, if any employee quits before the notice period, the Employer can only recover the Notice pay, and the Company cannot force to serve the entire notice period.

- Further, the resignation decision is the employee’s decision, and the employer cannot sue for breach of contract, if the employee leaves without serving contractual notice. 

- Except, recovery of the said amount, company cannot harm you for the same

- Further, no employer can refused to return the original certificates or to issue relieving letter .If they are doing so, their act is illegal, unjustified and against the fundamental rights of the employee.

- Further, the employment bond with the negative covenant is valid and legally enforceable, if the parties agree with their free consent i.e. without force, coercion, undue influence, misrepresentation and mistake, but it is not enforceable, if it is either one sided, unconscionable or unreasonable.

- Hence, you can pay for the four days , if you have already tendered your resignation , and the said company cannot take any legal action against you. 

You can contact me, if further suggestion needed. 

You can counter the said illegal things. issue a legal notice and file complaint to labour Commissioner office