MTN Horrifyingly *********** on every level!

I took out a MTN contract 3months ago which has 2 linked numbers on one account. one of the numbers is a Flexi 50. I have to buy extra data and voice minutes when it is finished. This I want to do by going on the APP and buying it on my linked profile so it gets added to my account. Or even with USSD code would be acceptable. You would think this is simple. It is impossible. For the last three months I have weekly been either in the MTN store (which is a very long process waiting to get into the store in Covid lockdown) or on the phone with customer care numerous times. In store they go on the system and say everything is fine. I must wait 24 hrs. Then nothing. It says my spend limit is reached. So I phone customer care. They then say they have increased my spend limit. wait 24 hrs. still nothing. I phone back. The new consultant says that my spend limit is too low, as my monthly base cost is R500, I must lift the limit to R700. She cannot do it but will escalate it. I will get a message confirming it has been rectified within 24 hrs. Guess what? Nothing. So I phone again. The consultant now tells me that she now REALLY has lifted my spend limit, but now they tell me to run a USSD code from my side to activate it. So I do that. It asks me to confirm my spend limit increase. I confirm. I get a message back that the system is down. Try in 15 minutes. I have been trying it numerous times for 2 weeks!! The message stays the same. I phone in again. No one knows what I am talking about. Just tell me to run the USSD code. I go into a store. Explain the whole story. Lady in the store tells me that she cannot help as the MTN system is down!!! I do not know what to do. Is MTN so pathetic that they cannot get their multi-million rand systems to work and actually get people trained and equipped with the right system support to do the most menial task of actually helping people to be able to spend money with the company???? I moved to MTN from my previous provider and is regretting every moment of it!!!