Putrid service

I upgraded my contact on the 13 January 2023 which was obviously the biggest mistake. I went about the online channel as it seemed very convenient however till this day I have not received the device yet Mtn was so quick to bill me for something I do not have, I paid end of Jan for something I do not have it's a whole month today. I sent countless emails called 100times just being sent from pillar to post...worst experience ever as I'm stuck I do not know what to do