Speedway review: access money being held

I am a constant customer at Speedway on St Andrews Rd Columbia SC 29212 and sometimes in Harbison.
On 11/29/18 I went inside bought 3 packs of Newport 100s and $10 of gas at pump #3 between 7:40 and 7:50am. I noticed the regular manager was not there and Miss Jacque Harrison was on the register.
My total was $27.87. I went to my next location and tried to get $40 cash back and was denied.
I had the cash on my Mastercard so there shouldn't have been a problem. I've used this same card many times and removed cash back at my next location with no problem. I always go in I NEVER use my card at the pump.
I should have not had an issue when I called the card company I was told you all had a hold on more money than what I charged and I would like to know why.
I'm thinking since the manager wasn't there that this has something to do with how the transaction was processed. You all have really inconvenienced me with this and I am extremely upset.
If you watch anyone it should be your manager who was absent who has such a peculiar personality that reminds me of someone who has addiction issues...ijs I guarantee I'm not wrong. I remember she tried to o ercharge me and blamed it on the computer. I'm glad my.mother sent me to school therefore I knew how to add and bought to her attention the error.
Back to the issue at hand I want to know why a hold was placed on my card. I'm angry that I'm unable to complete my daily task because of this.

Gayle Edmonds
Trans#1039881 Reg#1
Debit card
Swiped
AUTH
Approval code#584789