Not taking debit order then charging admin fees!

MY debit order was not deducted on the 25th as per usual, and now MTN wants to cancel my number and charge me admin fees because of an error made on their side. I have contacted support to let them know they can deduct the money off my account on the 25th as my contract states, but again they have failed to deduct the money. I refuse to pay admin fees on an error on their side. Also MTN is breaching contract when they do not take the debit order off my account on the 25th. They keep on sms'ing me saying I should make payment, baking details is on my invoice, I have read through the invoice and there is no banking details on the invoice.