Sold Property Account Unresolved

Our property was sold in Midlands estate and transferred to new owners 14 September 2015. Accounts of this nature are usually handled by an acute and controlled system through transport attorneys(in this case DE VILLIERS & PHEIFFER ING / INC) so the process should be absolutely trustworthy and transparent. Despite this and after numerous attempts (by personal correspondence) spanning four months we have yet to absolve our municipal account with Ekurhuleni to get our refund of reserve funds and deposit. It seems that we are being bound by the new owners not having registered a new account and we are still getting billed on our account for their services. Is it not ******** to keep billing someone who has relinquished the property and the attributing services through a recognized legal channel and process? What does it consequently require to get de-linked from a contract if not by legal process? Magic?