Airtel — transfer ownership

Address:

Thane, Maharashtra, 400601

Hi,

I want to know why is it compulsory to opt for 3 months postpaid service in airtel after transfer of ownership.

If there is anything in writing for the same, provide proof. I couldn't find it on trai website.

The airtel executive had no proper answer for my question and promised to send me a mail in writing. However there is no update from the executive.