Wrong advise provided by agents and now I have a debt

I had app**** for a fusion overdrqft account in July and it was approved. I later cancelled the card delivery and thought since i didn't take the card there would be no changes. That was my mistake. I unknowingly reapp**** in August and it stated that it was approved again. On the 7th of August 2023 at 11:00 I called FNB to enquire where should I send my documents to. I was advised that the fusion account was already active and I have an overdraft amount of R1000 that is available for me to use. I told the agent that a balance of R400 and something was appearing on my side and does that mean that I can withdraw R1400. He advised yes, based on this information I went to the store and attempted to withdraw R1400. The amount didn't go through so I ended up withdrawing R400. I called in afterwards and the agent advised it's because I am not using the new fusion card and I am still using the old cheque card. She placed a card order for me. Now I see a negative R999 and I called in and I was advised its because of my overdraft facility. I called in and I was advised differently how is this my problem now when I was ill advised by your agents. Do T&C state that even when I have been ill advised as a customer I have to be held responsible?