MTN Bad service

I upgraded with MTN South African at Liberty Promenade on the 17 July 2020. I have 3 SIM card in my name and my SIM card phone calls was due for an upgrade. The guy who was helping me was mistakenly upgraded the wrong number which not fault coz I specied which SIM card I have to upgrade and is due for an upgrade. I have been calling and going to the store to rectify their mistake coz now I have to pay more for an early upgrade for a number that was not due for an upgrade that I didn’t sign up off

I wrote to MTN inbox on Facebook and Twitter and they have been investigating the matter since forever and now they don’t reply to my text on Facebook. The mother at the store told me that they are not able to sort the matter, so what can I do when the service rendered to me is unsatisfactory. Should I accept mediocre because they are unable to help me?? My SIM card for data was cancelled during this process of upgrading the wrong number. I e-mailed MTN to assist me since the shop is unable but still they kept quiet.

The upgrade 20GB I never received and it was also pending for investigation since 17 July 2020. I regret for over upgrading my phone now I’m in mess