Frustrated and disgusted

On the 02 February 2021, I was told that my account is in arrears apparently the payment for June 2020 was not reflecting. Imagine that almost a year later. I managed to find the proof of payment and sent it to their collections team. Today 19 February 2021. I go over to the Festival Mall branch after standing in a queue forever I am told once again my account is in arrears- this time October 2020 payment is not reflecting yes after the 1st incident collections sent me a payment summary with all payments made from May 2020. I was turned away and could not do the sim swap - which was going to please paid with cash anyway... this is also not the first time this is happening a few years ago I had the same encounter with MTN South Africa. How can you be told a year later that payment was never received?!?! Is this really the service one gets after having a 10 year contract with MTN...