HTC — Demand of service charge in warranty

Address:

Surat, Gujarat

I have purchased the mobile of HTC model no. HTC Desire 616 five month ago which is out of service. I submitted the product to HTC service center on 10/08/2015. The service center representative asked for service charge even though the device is in warrenty period. Actually my bill is not traceable at present. My device is in service center and he says that if you present bill the repairing cost will be wiped out.