Money Disappeared from Account

Discovery bank. Please guys get an intellectual staff member to handle my case. This morning I had to pay an eft for a item that i purchased. I had " available" in my current account R741.69 . I then transferred R20 000 at 09:21am from my savings account to my current account to pay for the item i purchased. At 09:23am I made the purchase for R6726.21 and my "available" balance showed R6079.76 instead of R14015.48 . Somehow R7935.72 just disappeared into thin air.

I have contacted customer service and they tried to convince me that due to pending payments that i have previously made the "available" amount is correct.

I don't have an overdraft account. My account is on my phone so I calculate my spending very carefully. There is no way that i can swipe or withdraw any amount higher than my available amount.

This is also not the first time i have noticed it. I will have to reconcile my whole history to find out what is happening.

The sad thing is that I have helped and advised all my friends to open a Discovery account. Something I'm definitely starting to regret.