City of Joburg not refunding me for THEIR error

I own a small unit of 69 square meters in an Edenvale complex. Since some time in 2018 the CoJ started charging taxes for this unit in access of R2000 per month whereas before the taxes was less than R1000 per month. A third party handles my monthly payments and as such I only realized this sometime during 2019. After lengthy enquiring I realized that the 69 sq. m. residential property was erroneously re-zoned by CoJ as a business area. I submitted a correction review as per the advice of a letting agency after which this error was corrected. Since then I have tried many times but could not find anyone from the CoJ to refund me for the erroneous over-charge of about R1000 per month for multiple months.