Keep debting my account wrong amount

I joined Tracker in December. Since then Tracker has been debiting my account too much every month. I have phoned numerous times, been put on hold for ages and been promised that someone will call me back. Tracker has made NO attempt to fix the mistake that they made, never mind apologise! I keep having to be phone and follow up, retell the story a hundred times only to be put on hold or told someone will call me back! The service I have received has been beyond shocking and I am ready to cancel my services with Tracker if this is not resolved in the next 24 hours!