handed over incorrectly!

I sold my vehicle in 2014, I asked how much I owe in total and the money was debited. No communication between July and Jan 2015 as I know that I don't owe and contract cancelled. I got handed over because some *********** employee did not send CANCELLATION request in July 2014 but only in September and that's how I accumulated extra fees and now they are pestering with phone calls from rude collectors. I have been explaining myself to more than 10 people from last year July but still received a call on the 15/May 15. This is getting out of hand, what bad service! This is frustrating and customers can't be treated this way. I DO NOT OWE ANY MONEY.