Airtel — postpaid bill issue during port from airtel to jio

I port my airtel number into jio in april 2019. I made bill payment which was generated at that time.
After that a bill is generated again for the month in which no. Is ported into jio.
Their is no information from airtel and they charge late payment of 100 for that month.
Earlier the bill amount is 444 whose information i recieved in june 2019. But in august total bill amount becomes 881. When i call to customer care they said i did not make payment of november 2018. But bill genertaed after november they did not add the previous pending amount of bill in the bill cycle upto april 2019.
Please look in this matter and solve issue as soon as possible.
Regards
Gourav dhiman