FNB's service is truly pathetic

I upgraded my Cell Phone from an iPhone to an Samsung in January 2019. Since then (5 months) I've struggled the get the Authorization messages on the new phone when trying to do EFT payments on my trust account, thus resulting in me not being able to pay any new recipients or do instant transfers. I've called the contact Centre and went to the branch...and body can help me. Surely this should something that is happening daily! FNB's service is truly pathetic....I honestly do not know how to get this fixed, and apparently FNB do not know either.