A Really UPSET Client

I am really upset with Cartrack. I got letters from them that they will hand over my account or my account is blacklisted... I cancelled my account state that they can deducted an x amount , and every month they deducted tripple the amount some months even more! They keep on deducting money from my account. I dont owe cartrack any more money but they keep on deducting outragious amounts. I even have a paid up letter stating that i dont owe anymore. I want my refund within the next 24HRS!