Netstar please stop ruining my account or rather record.

Netstar should stop being *********** and ruining our credit record. I have cancelled their policy early last year. Then to my surprise somewhere in December and January they decided to debit my account whilst all along they were no longer debiting. I had to do reversal from my cheque account. Then I started receiving calls daily from them and I kept telling them one thing however it seems like they never listen and update their system and end up make it our fault. I cannot keep up anymore they keep on calling and at some stage debit my account without my concern and as far as I know I owe them nothing.