Blacklisted device without any reason

I'm not a believer of name and shame, but FNB has forces me in this direction now. My device was blacklisted, without any warming, notification or reason. I can not make any payments because I need to approve it on my app and I can't access my app. This is for my personal and many business accounts. I spent the last 2 days on the line, spoke to so many different people with absolutely no success. Webster told me yesterday at 12:00 that my app will work by 15:00, it's still not working. Now they tell me I must wait 2 - 3 days, but still no answer to why my device was blacklisted. I'm currently for the 5th time today on a call of almost an hour and nobody can assist me. This is really ridiculous!