Cartrack making customer pay additional fees for them

I was charged extra for moving the account to the new owner of the car I sold. They kept on hassling me to pay account transfer fees, the same day I paid the fees they also did a debit order which was more than the initial/agreed amount. If I never saw that they would not have refunded me but also they are only refunding me the amount I paid instead of the amount they deducted. They say that it's a resubmission fee of which should not be mine to pay nor my problem. If they are doing this to customers, making us pay for their transactions then that is wrong, why were these fees never app**** when I was paying my monthly premiums and also was not communicated when they were hassling/spamming me to pay for something even before the end of that month. For those reading this please be aware of them taking advantage of you/customers