They are playing games and best way out is to put all dates of joining as probationer and when probation should have ended and on what date you have resigned.
Raise the level to HR HoD for clear answer.
Intimation of confirmation not being sent to you is a mistake from company side and you need to stick your stand and give 15 days notice.
Thanks for the reply. However i applied resignation on 11th may and as soon as i put my resignation in tool, i got mail for confirmation. When i applied resignation the date of relieving was 25th may but today when i again checked it has been changed to 5th Aug and notice period is extended to 90 days. The confirmation letter states effectiveness from 12th may and i put down my papers on 11th may. I am worried they will ask me to serve 90 days which is not possible. Please Help.