Cognizant — taking a lot of time for my resignation which is unusual

As promised by my batch owner, that it will take maximum of 7 days for my release from the company, but it's taking a lot of time for my final release. And after repeated mails made to the concerned batch owner, now he is telling that the final date is not in his hand. Then what is the reason of this fake promise which made all my plans doubtful.?