Alleged outstanding account with Emfuleni Municipa

I keep on receiving SMS's and e-mails from MBD attorneys regarding an alleged outstanding amount with Emfuleni Municipality. The more I explain to them that we have sold the property 3 years back already, the less they understand and the more requests I receive for payment. I tried to respond via e-mail to the e-mail address provided on the demand, in order to sent them copies of the transfer documents, etc, however the e-mails keep on coming back as undeliverable. I also phoned and got another e-mail address - this also does not work. Prior to this I phoned and spoke to a lady - Fransien and I requested statements of account. She said that she will request it from the municipality - 5 months later and still nothing has been received. I don't know who's worse the attorneys (chasing the money) or the municipality (enough said...)