CoJ Uncontactable - Customer Assistance Required -

I have received a call from a debt collector telling me that CoJ have handed us over for a rates amount of R35000. Our account is currently in the black as pensioners over 70 we do not pay rates and moved in recently and are in credit to CoJ. I am unable to contact CoJ - I have four contact numbers published on their website and on the internet all are saying “this number does not exist” so I am unable to find out if the debt collector is legitimate and CoJ are response for the error. I need urgent assistance.