Lenovo — ideapad 500 15isk

I have registered for back to school offer which provides additional 2 year warranty. After confirmation form lenovo i have paid the inr 800 to avail this benefit on 14th june and on 19th june 2017 i have received the confirmation mail for payment receipt. But till date i have not received any warranty certificate from lenovo even after multiple follow up. Only they are repeating same wording every time as below or give some date
Quote
"thank you for registering for lenovo back to school offer.

We sincerely apologize for the delay.

We will make ensure that warranty certificate will be shared you on priority."
Unquote on both email and phone.