FNB blocked payment because they cannot update my details!

I have been trying to change my cell number on my account since the start of May as I get an error message when I try to do it myself via online banking and the app. Three complaints later it has still not been resolved and now FNB has stopped an important payment I made on Monday because they tried to verify my identity by calling me on the cell number I am no longer using! I have sent online enquiries, emailed, phoned and complained several times and each person who picks up the issue vanishes on me without having resolved the problem and I’m now unable to make that urgent payment again as don’t want it stopped again for the same reason even though FNB have told me it’s ok that the payments team have my new number - then why has it not been updated on my account details, the old number is still showing on my account. I am completely appalled by this service. FNB please sort this out???? I need to make that payment urgently today Friday 11 June.