wont stop trying to take my money

I have cancelled my Tracker Agility services twice and still they withdraw money from my account even though I reverse the transactions every month. I just want them to stop!!! I have long since cancelled the service and they keep running the debit order every month!!!! and every month I go into the bank and reverse it. PLEASE JUST cancel my account and stop trying to make me pay for services I no longer want or receive!!!!!