Airtel — internet speed deduction and drop in voice call quality

Address:

Pune, Maharashtra, 411048

The internet was working fine then suddenly from 3 weeks the internet speed was dropped, almost nil. I wasn't even able to access google. I had lodged a complaint through customer care but they misbehaved then i went to airtel gallery to change the sim (As i thought it could even be my sim's fault), still no change in the internet speed. I am only able to use internet at night, for the rest of the day the internet doesn't work and the voice quality since then has also dropped significantly, kindly resolve this issue or refund me for my loss!