Not Getting Relieving Letter but send Termination Letter by Employer

Dear Sir This is inform to you that myself working a finance company they are provided me termination letter after 7 days of leaving the company even they are accepted my resignation letter and doing the all exit formalities and then send the same. they are reason showing the reason the letter is duplicate signature in sanction letter but not any information to me at the time within service and after service period.After this letter same day i was mail send the to the HRD and Management to what reason or which case doing this they are not replying me anything and then one day called HR and Business Team and say u send a mail for withdraw the same escalated mail then we are providing this but i cant to accepted the do this and the next mail when i send i saw my mail id is block to send the mail but at the same time i was mailed to the all mail id full chain mail from my other mail id.Now issue is that my current organisation ask me for the relieving letter but thay are not responding anything to me Kindly suggest me or help me for the same situation and what is the next step to do and getting the relieving letter Regards Manoj Kuila