Gym Company's Pathetic service

I opened a gym company account last year June paying R199 per month. After realising I would be moving residential areas I attempted to cancel/transfer my account to another individual. A gym company consultant assisted my friend and I with this request we paid R300 each for the process. After realizing that even after transferring the account we were still being billed we contacted gym, who provided bad service who told us to freeze our accounts and they would investigate. Nothing has been done. Even during the freezing period they continued to attempt debitting us. We have even stopped all debit orders from gym company and they have now started sending sms's threatening to blacklist us. We have tried to contact their management yet nothing is being done. They keep telling us that they will investigate.