MTN refusing to do a SIM Swap instead I am always requested to pay

MTN South Africa is refusing to activate my SIM card after I lost my phone. I was owing them but have paid them in full but still I am unable to do a SIM Swap. Instead we are just going round in circle with no joy from their side. Whenever I make a follow-up I am requested to pay and they will confirm that it's sorted. Still it will not be sorted. I will do another follow-up and I will be told that there's a new invoice you have to pay prior to being assisted with the SIM swap but again it will not be resolved. I need the MTN legal team to amend my status to active and move the account to "normal accounts department" as I have long paid the money I owed.