No one updated my banking and contact details

I went into the Midlands Mall MTN to update my banking and contact details as it has all changed, I see that at the end of the month MTN tried to debit my old account that I no longer use, I have gone onto the website and sent two messages without anyone getting back to me? So now I have not paid for the contract this month and no one has contacted me? I want to update my contact and banking details so I can pay for this contract. Could someone please get hold of me.