Poor customer service from clearwater branch MTN and still no resolution to query for 3 months

Please note that I upgraded my contract with MTN on 12 May 2018. it came with a Huawei mobile router which supposed to have 500MB of data loaded monthly. the problem is that this was loaded incorrectly by the sales agent and R50 airtime was loaded on the device monthly. I reported to MTN call centre who advised I need to take this up with the branch, Clearwater where I took the contract up. I followed up 4 times with the branch who advised me it was rectified however this is not the case. it is now 3 months later and it has still not been resolved. I cannot use the data monthly on my device the sales agent , Bianca Campbell and the supervisor Tumelo was not successful in resolving this and never got back to me. it was always me that needed to follow up. when I call in to the branch, they advised that they will resolve and give me feedback but nothing has been received to date. I even got them to copy me on an email to the relevant accounts dept to resolve and also sent emails myself but this has not been resolved as yet. this is totally an inconvenience as its a waste of my time and money as I don't have the data and I have to drive each time to the branch to see if they can resolve and they do not help.