FNB cannot assist with a simple debit order change

On the phone for 40 minutes with FNB being transfered to 8 people, none of whom can assist me with a very simple request!

All I want to do is change the banking details of my debit order for the retirement annuity I opened up with FNB. Not complicated in my opinion.

Eventually I was put through to Momentum???!!!

Thats when I gave up.

Need someone to assist with this please.