MTN credit and debtors apartment are USELESS

MTN does not know how to do invoicing or handle peoples account. They are USELESS. In Feb 2021 I did upgrade from DATA contract to normal Talk S package. On the OLD DATA contact was 30GB what I received every month and with the new contact that 30GB must fall away because I am on new contact but this was to difficult for MTN to under stand. What is also sad , MTN bill me for the 30GB on the new contact but don't received it. I was struggling from March 2021 till December 2021 to explain to MTN what happen and every time MTN let me they removed the 30GB till I received my new statement and BOOM the 30GB is still on. In December they gave me my credit and the 30GB was still not remove. So from January till March was I tried to explain again and still no one can't understand. In March 2022 I talked to Supervisor and told me he will handle the situation and he will fix it. The amount for the Talk S package was also for the wrong amount and they luckily fix that. This Morning, 20 April 2022, I received my new billing and BOOM the 30GB are still on the invoice. I can't understand why is it so difficult for big company like MTN that can't even remove a simple 30GB and if you don't pay your account on time they cut your lines immediately. I have 4 lines active with MTN and VODACOM will see me soon.