Videocon Industries — not providing the bill

Address:

509, Parijat chs, plot no 54, Sector 21, apj school road, kharghar, 410210

Hello, i had recently taken the service from videocon d2h to reinstall my dish as i shifted from one place to another. They told they will charge rs 450 for reinstallment. (Customer id:[protected]
But when technician came he said he will charge rs350 extra as some part is missing (Nothing was missing, some minor thing boalt or sckrew they added extra from their side). At the time of service only senior citizens were at home so they didn't ask for the bill they simply gave the money.
But when i called videocon and asked for the bill they simply denied for providing the bill and gave some useless reasons like they don't have policy, they don't keep records for what technician does, etc..

I'm tired of calling them asking them for the bill. I'm attaching the audio conversation which we had.

I want my invoice for rs800 with price breakdown.
What extra part they replaced and how much it costs.

Looking forward for your help.

Thanks,
Priya mawade