Mts bill payment

Hi Kaanoon, I have used a MTS dongle for internet. atleast i have paid my bill smoothy. When i pay for fourth time with Paytm transaction failed and my money got refunded immediately. After that i have made the payment throught MTS online payment with my SBI account. MTS reported that they didn't recieved the payment but for me transaction is successfull and amount is debited from my account i informed the same to MTS number of times. They said me to re-pay the amount again. But i refused as the transacted money was not credited to my account how can i re-pay it. Due to this MTS deactivated my account with in couple of days. So i have written so many mails(12-15) to the customer care but no proper response from them. Finally i follwed up with SBI and escalted to higher management then they successfully processed my transaction and they paid the bill. But now MTS has sent me a notice that due to delay in payment and one month extra bill which i did not used. they are asking me to pay it. how should i proceed with it.