Airtel — Excess bill amount charged and bad behavior by the executive

I’m using airtel postpaid sim. I had called and activated an additional data pack for a month. I was told by the executive to call and remind her on the day I receive the bill the next so that she can deactivate it. As soon I received the bill I’d called and asked her to deactivate it and she’d confirmed telling that it has been deactivated. But when I got next months bill it showed that it wasn’t deactivated and I have to pay extra 300 rupees approx. As soon as I got the billing showing this I’d called her she said she’ll see to it and shall file a complaint. I waited for a week or so and still there wasn’t any change in the bill amount. So I called her again. She stopped picking up my call so I texted her on WhatsApp. I did not call her every minute to disturb her I called her just to enquire but She blocked me both on her phone and on her WhatsApp. I didn’t want to pay extra money for not paying bill on time so I paid the amount. I paid the amount only because I contacted another executive and he said he would waive the amount on my upcoming bill and that it was her mistake. Next bill came and the 300 rupees I’d paid extra was still not returned. I again contacted the executive but he didn’t respond. Again I had to pay the pill because of the due date. Please kindly take my request into consideration and do the needful for cheating me.