Tikona Infinet Private Limited — I requested to disconnect my connection but they have stopped rentals

Dear sir,
I was a subscriber of tikona internet provider in pune for about one year. I requested them to disconnect my internet connection on 22nd april, 2018 since i was relocating. I have called the customer care tens of times, mailed them multiple times to disconnect. I have recharged on 30th march for april month. Even i have used till 22nd april well before the month ends. Instead of disconnecting, they have stopped rentals only and send me a bill for may month with late payment charges.
They are doing fraudulent practices by sending bills. They said to pay for only 15-22 april month as their billing cycle starts from 15. Instead of sending me a bill for one week. They sent me for whole one month. Now they are charging with late payment charges.

Kindly take the appropriate action as they are doing the fraudulent practices.