Airtel — balance deducted for "unused data" due to some technical glitch

Dear Sir
I called customer care at 121 twice and got a thoroughly inappropriate answer "we have told you we cannot help, do not call again".
I had balance around 200 rs and suddenly its gone. My data connection is off, I have not made any calls in last 3 months. They checked and said it was deducted on 3rd June 2018, which I refuse to believe since I did no such thing. Its some issue in that area for all providers (Jio etc.), it shows MBs consumed for no reason, even when data is off. I got no SMS about the deduction or data usage since I get an SMS for every 10MB consumed. I have proof of such previous occurrences.
I demand refund and to find out where the data was used and they ask me to shut up.
Yes it is not possible to check personal history but how else can I prove that I DID NOT use internet services?
Something similar happened before and somehow I convinced them otherwise to go to police station to get the browsing history.