Terrible service from Mrn

Good day, When my contract on this number came up for renewal in November 2022, I elected to change the service back to prepaid. Once this was done, I experianced numerous issues with the service. I visited a branch (K90, Boksburg) who recommended that I do a SIM swap as my simcard was very old (around 20yrs). This could not be done as the SIM was apparently still blocked at the MTN Retentions department. This has been ongoing since the beginning of December. The K90 branch have send numerous mails and has received no feedback. I have tried numerous times to phone customer care as well as retentions. IF YOU GET THROUGH to them, the service is absolutely shocking to say the least with 'I DON'T KNOW' the standard answer. That is now IF you can hear the consultant over the back ground noice of people shouting at each other or children laughing and playing. According to the person at retentions, there is no reason why I can not do a SIM swap and I must be doing something wrong. I tried to do a swap online and the system does not allow me. I tried contacting Mtn via facebook with similar results (nothing wrong, I'm making a mistake). I went back to K90 today and according to the staff, it still shows that the number is on contract which means I can not do a SIM swop or even change my service provider. They have once again send a request to retentions to release my number. This is the 3rd request from the K90 branch!! I am really getting tired of this shocking service from Mtn. All I want to do is a SIM swap. Can someone PLEASE assist me!!!!!!!