Service Cancelled but Billing Continued

I cancelled my ADSL line service on the 5th October 2017 and received a SMS on the 23rd October 2017 advising me that Telkom is saddened by my decision to cancel and hopes I will reconnect again . Apparently the service was cancelled and then reconnected the same day and the billing continued . After following up and escalating this the service was finally cancelled and Telkom advised me by SMS that my account has been backdated to the initial request date ( Ref: ********** 76A) . However this hasn’t been done and my account reflects that im in the negative by 2k . I only discovered this when trying to purchase a new car as my finance was rejected because of my Telkom account .

Who can i contact to get this urgently resolved ?