Probation extended after completion of Probation Period without prior notice

Hi, This is Ujjwal Kumar, currently working in Meritnation as a Faculty from last 6 months.
The issue is, I joined this organization on 23-11-16, and my probation was of 6 months, which was to be completed on 23-05-17. When I completed my probation period, I checked my ESS account for confirmation, but there wasn't any.
I emailed them on 01-06-17 regarding that, which I got reply today that my probation period has been extended for next 3 months(Also only today I am told to resign on the grounds of company benefits(cost cutting))
What should I do?

Dear Ujjwal Kumar,
Have you checked your appointment letter for the provisions of probation and termination of services during probation period? What is written in the appointment letter?
As far as rules of probation are concerned, employee's probation can continue up to year. Therefore, nothing wrong if your company has extended probation. Even discontinuation of services also could be within the provisions of the appointment letter. However, further clarification can be given only after your confirmation.
Thanks,
Dinesh Divekar