Updating Banking details via your Discovery Portal - Doesnt work

Wow, wow, wow, what a frustration. I need to update my banking details as I changed banks. I followed the online portal bot steps. Up to this point it's easy and effective BUT now the portal doesn't want to accept my new banking account number with a VERY blaze error [Bank account details]: Invalid Account Number

Which I can confirm is not the case as this is a valid account number I have entered. The other BIG shortfall of the portal is it doesn't give you contextualized help/assistance.....and to try to speak to someone is almost impossible.

How on earth can something so simple be so complicated Discovery. All I want to do is to change my banking details for my 3 product portfolio's I have with you. Its not rocket science