MTN can close their doors

So... I have a contract with MTN on a month to month basis (after another irritating experience with MTN and DSV in Nov 2020 I decided not to upgrade). I'm the contract holder and my wife is using the phone. Since Saturday the 28th of August, my wife can not make any outgoing calls. It keeps on saying she's got insufficient airtime, although the contract is on minutes and there is 89 minutes available. I started phoning MTN on Sunday, every time they tell me it will be fixed after I switch the phone off for 5 minutes. And it never happened. Today, after the 11th time that I phoned since Sunday, they managed to fix it, but it lasted not even 2 hours. I phoned AGAIN just after 4, and the lady told me she can not fix it. So I have another reason to cancel this contract with immediate effect. Will you fix it or can I add another horrible review to your list???