Payment from FNB to FNB Inexplicably Delayed

A customer of mine made payment to me from his FNB account to my FNB account using FNB's app, ie it was done via EFT. It has been hours and the funds are still not reflecting in my account. I have verified the account details used and has the client showed me the Proof of Payment on his FNB app. I phoned FNB and is their only reply that it can take anything from 5 minutes to 24 hours for the payment to reflect in my account! FNB is the only bank that I know of that has a delay on payments between its own accounts - it is unacceptable! My FNB account is a fairly new account and am I seriously considering closing this account and going back to Absa!