Incompetency of banks

On 15 August 2022 I made a purchase using my Nedbank debit card, it was a substantial amount, the card machine declined the transaction for no reason, but the funds left my account immediately. I phoned Nedbank for assistance, and was given no explanation, and was told to wait 2 days for it to clear, which I could not do. I then went to the branch in Vredenburg; same story, but the lady who helped me said she would investigate and contact me the next day, still waiting. Fortunately, the supplier was lenient enough to let me take my car with the 4 new tyres, on the understanding that I sort out the mess ASAP. This is absolutely unacceptable, and I demand an explanation as to where the money went to, it's like someone stole my money!