If new policy of 3 months notice was not communicated/ supplied to you and was not accepted by you in writing, you can contest it, and submit your resignation as per original policy stated in your appointment letter. You should mention the effective date of resignation in your resignation letter. On the effective date you should submit your resignation (under proper acknowledgment with seal and signature) addressed to your appointing authority or send it by regd/speed post with AD. If AD is not received back by you, you can obtain POD from PO. If PF number is not stated in salary slip obtain it writing (by email or by letter) from company, before leaving the company.
Before or on effective date of resignation submit company property and obtain proper acknowledgment and use your rapport goodwill to obtain written comments that no company property is due and no assignment/project is due to be completed. This can be be as good as NDC/NOC
If your reporting authority has signed your resignation letter and you have the copy with his signatures, this would imply your resignation has been supplied to company. Company reserves the right to accept the resignation.
Company can sit on relieving letter. Company can not withhold service/experience certificate, form 16,F&F,PF accumulation reports, PF forms. It is better to transfer than withdraw the PF as after 10 years member becomes eligible for pension.
New employer can absorb the new employee on the basis of acceptance of resignation, NDC/NOC, service/experience certificate, F&F.