Bad attitude poor service

Tracker has been deducting money from my account even though I settled the account, they now threatening to take me to debt collectors even though there is a proof that I settled the account, I have a letter sent by tracker by email after settlement has been made, I phoned them they confirmed that the account was settled by (MAY) closed and cancelled but they still want me to pay the account *****,bad services I experienced I will never refer anyone to tracker it is a BAD service indeed ,i would really advice those who are still using tracker that you in trouble that company is not good look for something else it desperate for money, how can they still deduct from a customer whom by their records has settled the account