Confused about random outstanding debit card registration fee

Hi there. I’d love to understand where some of the money in my account has gone off to.

I have a transact account and I am a student and my online banking account details are confusing me. I was told that a transact account had the lowest fees which was suitable for me as a young student. However I have come across R300 missing from my account and my transaction history states that I am owing a fee of R300.28 for outstanding debit card authorization. Please inform me on what this is as I was previously told to not expect fees of this amount. I would really prefer to fix this issue without any problems as I find it unsettling when I don’t know where my money is going or why.

Thanks