MTN incorrect debit order unresolved

I have renewed my MTN contract at Forest Hill branch on 8 June 2020 with contract amount R449 monthly. Since 1 July R620,55 is being debited from my account. I have been unable to resolve the matter after numerous calls, visits and messages to the branch, the manager, head office and their customer care service. The last time I visited the branch I was told that "you are not the only one" and that I "should reverse my debit order" if I am not happy. The reason given for the matter not being resolved is that the account department is working from home due to Covid.