Amazon.in - Mobile phone handset not valid

I purchased BlackBerry phone from Amazon.in in January '** .

Product name: BlackBerry Priv


Now when I want to claim the warranty the service center denied the same saying that Imei no. Of my device is not listed in their entire database.

Same issue I informed the Amazon customer care on **/**/**** and was told to wait for **-** hours for solution.

After waiting for * days when I received no communication from Amazon I contacted them again on **/**/**** when I was informed that I needed to provide proof of denial from BlackBerry .
I immediately provided the contact no. Of service center where I visited in order to facilitate transparent communication.
The call was held up stating that they have noted the contact no. Of service center and will be contacting them on their own and I will receive a solution within **-** hours.
Another * days passed and I contacted amazon again yesterday i.e. on **/**/****. When instead of an apology in delay I received a blunt answer that they can't provide any further solution unless I provide a written mail from service center as a proof of denial which was not demanded on **/**/**** & I kept waiting for * days trusting the procedures of Amazon customer service.
Yesterday itself I provided a written mail drafted from the BlackBerry customer center end denying the service due to Imei not registered in their database.
But now when I called Amazon again a different service executive had a conversation & they had an audacity to ask me for a hand written physical document of denial or else they won't be helping any further support regarding the matter .
Same repeated conversations are occurring every * days but yet after ** days no solution has been provided






I am Medium manufacturing Enterprise and can't afford to waste my time on follow-ups with Amazon.

I request an under-warranty replacement or refund on the phone (whichever feasible)