Cognizant Technology Solutions — offer letter is not received.

I have interviewed and cleared all the rounds in cts chennai on 9th feb for pl/sql, in the hr round salary discussion was done, it has been told that you will get an offer letter in a 1 or 2 weeks but this is third week still i didn't get any offer letter.

Now again i am getting call from cognizant for the interview for the same position.

Any help much appreciated. Thanks in advance!!