Very Angry Customer

I make my payment on the 27th of every month, have done for the last 3 years. Since the beginning of this year MTN have suspended my account every month twice a month, i have to phone them to get them to unsuspend the account because i have made a payment. Then the very next day after i have paid they suspend the account again, and again i have to phone. They say that I have to phone every month on the 18th to make the arrangement that I will pay on the 27th. I made the arrangement this month to make the payment on the 27th as I do every month, I paid at 7:14 on the 27th and on the 28th I had to phone them again because they had suspended my account. This is getting ridiculous, with the technology of today, they cant make an arrangement or a note on their system to say that I would be making a payment on the 27th. I cannot afford to phone 3 times a month to get my account suspended, when I have been making my payments on the 27th of every month and it has never been a problem. This is the only form of communication including banking, and I cant do anything when they suspend my account.