MTN CANNOT FIX CLIENTS ACCOUNT

Phoned MTN since 31 March 2019 due to wrong invoicing. Spoke to 6 call centre agents up to 3 June 2019. Problem still not fixed. Calls get logged and resolved, when I phone back I get told they have fixed it and they five the correct amount which will be deducted from my bank account, but yet again the wrong amount gets deducted. I am sick and tired of phoning without my invoicing getting fixed.