Switched off for no reason

Mtn suspended my and my husband's Mtn account due to non payment, however we had made payment at the beginning of the month and the payment was successful. When I called this morning, I was told that there was an outstanding payment from July. The lady I spoke to could not give me a solution except to tell me I could make a payment arrangement. My debit order goes off on debit order, so it seems like there is something wrong with your systems. My app tells me that I don't owe anything until the end of the month.