Dissapointed Customer

I have currently been trying since last year July to solve an issue where MTN have been over charging me since April 2020 . I have been to the Tokai store since July 2020 , today it is March 2021 over charge issue still not resolve I phoned head office as well. Month in and month out they log tickets . Not sure what more to do. Their customer service is really socking and based on that once this contract is done I will no longer do business with MTN. Clearly they don't value their customers otherwise things like this would have been resolved.