Unpaid debit order

Hi fnb, you made an error and credited my credit account with an un paid debit order, this has caused some issues on my side. I was first called by your representative on the 13/05/2021 and today I have contacted your chart service, both cases I have been given different views of the matter, but it now clear that there was an error on FNB's side as this amount that was credited to me was not supposed to be credited, now the funds were used by me unknowingly. Issues is that we need to make arrangements on a way forward, the chart service consultant by the name Candice has ignored my message hence I'm coming here lay a complaint and she rudely just ended my chart