Bad service

What's the point of having the mtn app as a method of payment if when you pay, you still need to provide a proof of payment. I changed my banking details for the debit order only for mtn to attempt to debit the money from the old account which was not in use. After the debit bounced, I went to the mtn store to yet update my details and make payment arrangements. I was told that I can make the payment via the mtn app, which I did. I made the payment later on Friday 29th of October, but my number got suspended. When I called I was told that the money has not reflected and I need to send in a proof of payment. I sent the email confirmation as the mtn app does not provide a pdf format of the payment but I was told that I can't use that. Today 3 November the number is still suspended, the money has not yet reflected and I am told I need to go to the bank to fetch the proof of payment. What was the point of being advised to pay via the mtn app.