Debit order issues.

I was told that by downloading Nedbank mew app, I could reverse a debit order easily and avoid getting charged the R5 fee when calling and doing it over the phone. But the debit order reversal on the app doesn't get processed and when I call to ask why, they process it and charge me R5 because I called. I am really getting annoyed. The reversal should happen within 2 days of when I put it on my app!!!