Airtel — Wrong billing consistently

Address:

Airtel Store , LBS Marg, Mulund West, Mumbai 400080, Maharashtra

In June 2021, the store officer at Airtel agreed with me on a plan of Rs.999 + tax for 5 connections - 4 were voice + data and 1 connection was data only.
Accordingly I followed all instructions from the store office Mr. Sameer.
When I received my 1st month bill which was incorrect and which I got it corrected by visiting the store & paying the agreed amount. I was promised that the next billing will be correct, however the next month billing was again wrong. I visited the store again last month and was assured of reversals and correction in the billing. Given these assurances, I paid the agreed amount.
Again this month the bill is incorrect and on contacting the company on phone and through personal visit, I am now told that the correction is not possible.
Mobile services, in the current situation is part of essential services, however the company is clearly taking advantage of the situation and fleecing customers by making wrong promises and breaching the trust.
Would appreciate if appropriate action is being taken and my issue resolved.