Item not paid deducted on account

I have R125 deducted on my account and reference says item not paid 9n the 29.05.2020.

I have spoken to a banker on the app and was told that my purchase of the 25.05 2020 at Jansen of R993, but that purchase was done on the day I got my salary and it had reflected on my account.

I explained this to him and he said that the amount was reserved and I had spend the reserved amount because the amount was not deducted on my account yet.

Question is how can I spend reserved funds ? I have always purchased in different stores and the funds would be reserved and will go off my account even after 7 days however i have never been charged a fee for item not paid because that amount is RESERVED and if its reserved i cant spend it.

Please refund me back my R125 on my account as i do not think you have a valid reason for deducting.