New cellphone FNB app activation

I recently upgraded my cellphone. I attempted to reactivate my FNB app, but never received an OTP. I contacted FNB's number that the application gave me, followed the online help, but still did not work. I then spoke to someone on the FNB helpdesk who suggested rebooting the phone and clearing the cache among other suggestions of which none helped. I then called again and was told that the problem lies with the cellphone service provider. This seems strange since I receive SMS' from Nedbank regularly without a hitch. Perhaps I need to swap banks??? I have to say that FNB are the most useless bank I have ever had the displeasure of dealing with. If you are reading this message and contemplating switching to FNB, I strongly suggest that you don't. They can't fix something as simple as their banking app!!