Airtel — extra bill has been charged on my account

Address:

Hyderabad, Andhra Pradesh, 500085

Hi i purchased 6 months advance rental and got the postpaid connection with number: [protected].
I clearly paid your customer executive the amount of 3600 for the advance rental plan. I dont know what mishap happened between your executive and billing but i got the extra bill saying i have to pay 4248rs.
While i have to pay 648 only gst amount. Disgusting service and network we can keep a big 🙏 to this network.