Cartrack accounts department 🚮

I have absolutely had it with cartrack. Whoever is heading up the accounts department must do better. Since the 13th of December I've had to deal with their incompetence. First they debited my empty account because other people got paid early and I don't understand how that concerns me because I did not get paid early. Then I paid them because they sent messages asking me to pay them before the agreed date, they then continued to debit my account even after I paid them, I reversed the debit order because I had already paid them. But now they are harassing me with calls and messages asking me to pay them. I honestly can't wait for my contract with them to end.