CAR TRACK BULLIES

I was using car track approximately for like 2 to 3 months of whick their debit orders changed dates and there was endless penalties until I decided to cancel the service and reverse their Debit orders. They added another installment after I canceled claiming it was already added. Now they have been calling non stop for Me to pay. I have been paying monthly what I can afford now they are threatening to blacklist me. Which ombudsman is the right one to report them because they are abusing their power considering I pay every month.