abuse service

I cancelled y contract with cartrack because they used to deduct different amount in my account that we did not agree on and even cancelling the contract and made arrangement with them to pay manually ,they will still come to my account and deduct different amount .i called different department and they all promised to sort it out but every month 3 different debit order will go through .sometimes they wont be money in my account and bank will charge me R115 for each debit not returned unsuccessfully . iI regret having contract with them. They treated me badly and i wonder how many people are being treated like this .