Bill debited two times, still not refund extra amount.

Hello,
I am Vardhaman aitawade. I have Airtel postpaid number 9096921516 (Maharashtra).
On 2nd December 2017 I converted it postpaid to prepaid with paid all the outstanding amount by using netbanking at Devidas Airtel pimple saudagar pune.
My outstanding amount is 640/- RS but same time my account debited two times. (640/- RS + 640/- RS)
I can complaint immidiatly to Airtel, they said extra amount will sending you at billing address by cheque, within 45 days.Today is almost 60 days completed ,But still I can’t get cheque. so I called Airtel customer care, people are not responding properly, and again they said wait more 90 days.
Kindly requesting you please resolve this problem as soon as possible.

Please find below mentioned transaction details.

1. 101712011522775/CITRUS AIRTEL
2. 101712011522847/CITRUS AIRTEL