Airtel — Xtreme black

I have choosen xtreme black last month and paid 3300+ to the airtel executive where as it includes the plan 1019 (unlimted call and data for 75 gb upto 200 mbps) for 3 months and for very next month i got 1100 bill for xtreme fiber and postpaid bill for 510 which i was surprised beacause there is no plan for 1 month how can they generate for 1 month, even i am calling the customer care 121 they asking me to pay the bill, i lost bills from my phone, i have only the payment proofs even i asked my airtel execuite to regenerate my bill but he denied to answer my calls as well, also with there frequent disconnection my work has been effected not at all happy with the customer service
my register number is 8686***91 with airtel postpaid (disconnected my all calls )