City of Tshwane billing for a Property not owned

The City of Tshwane has been billing us for a Property which has never belonged to us. We have been receiving Statements and legal notifications dating back to 2014. I notified them when we received the first statement, and was told to prove it???? I eventually had to pay a Lawyer to submit a formal letter along with a title deed search on the Properties we own. For more than six years now I have sent emails, communicated telephonic-ally, submitted queries on their website to both the customer care and legal department. I have either received a notification my query has been escalated, or have had no response at all! I submitted a query last month again on their website, and received a response that, due to the lockdown they are not dealing with Account queries, we must pay our accounts and we can query it once they are fully operational again. They sent Statements and Legal notifications during this period, but conveniently their Customer Care Department was closed. I am now at my wits end, I have tried every means possible to sort this out, including paying a Lawyer. I'd appreciate any advice on who to contact to prevent been black listed, and how to find out who actually owns this property.