Terrible Billing and Customer Care

I have had contracts with MTN for many years. My main cell number was always used as my reference when making my monthly payments via EFT. In September 2024 I renewed my contracts but changed my main cell number from contract to prepaid. As mentioned, before I always used the above number as my reference and the monthly payments were always allocated to my contracts. On 24th June 2025 I made my normal payment using the above number as reference. On 11th July I received a call and sms from MTN saying I have not paid my subscription for June 2025. I called MTN customer care and explained the situation to the MTN customer care agent and she advised me to send an email to their back-office support team. I waited over 2 weeks for them to resolve this issue and on the 1st of August they said that they have resolved the issue. On 24th July I made my normal subscription payment again but now using the billing account number as advised by MTN. On 8th August I got a sms again that I owe MTN, and my number have been suspended.