Incorrect Billing

My 36 months contract for my television I rented from Teljoy came to an end in April 2015 and ownership was given to me. This month on my invoice I noticed that I was billed R85 for an ongoing service fee on the television without my consent. I contacted the accounts department today and a lady by the name of Gwen informed me that the customer care department was supposed to cancel the service fee when my contract ended. What you are doing is \*****". I am going to name and shame your company on social media if this is not corrected immediately"