Product: Credit card or prepaid card

On XXXX I went in to the XXXX XXXX station to purchase a pack of cigarettes, they scanned the cigarettes ( {$10.00} ), I requested {$20.00} cash back to total {$30.00}. I entered my pin number and the transaction came back declined. I pulled up my account on the mobile app and seen the {$10.00} ( the cost of the cigarettes only ) was pending. I showed the cashier my phone that the transaction for {$10.00} looks like it's going to go through, she reassured me that the transaction was declined and the {$10.00} will fall off and not post. Since that amount was frozen, I had to transfer more money in order to buy a pack of smokes and get {$20.00}. She rang up the transaction again {$10.00} for cigarettes, I entered my pin number and requested {$20.00} cash back and the transaction was approved {$30.00} The next day XXXX I went in to the same XXXX XXXX  to buy a pack of cigarettes and to get cash back, she scanned the cigarettes ( {$10.00} ), I entered my pin number and requested {$20.00} cash back, the transaction was declined. We tried the transaction again requesting {$19.00} instead of {$20.00} thinking maybe I didn't have enough in my account for the whole {$20.00}, again the transaction was declined. I stepped aside and pulled up my account to see why they were declined and noticed that both of the transactions for {$10.00} ( cost of the cigarettes only ) were pending. I told her that both transaction 's were pending and looks like they are going to go through, she told me that they would fall off and not post because the transactions were both declined. Since the two transactions for {$10.00} was frozen and no longer available I didn't have enough funds in my account to try the transaction a third time. I left the store without any cigarettes. 
On XXXX I pulled up my account to see if the funds were released and seen that both transaction on XXXX went through. The one for {$10.00} ( the transaction that was declined and was told that it would fall off ) and the one for {$30.00} ( The transaction that was approved ) these are the same transaction but the one included the cash back amount of {$20.00}. and the two transactions that were declined for {$10.00} on XXXX actually posted also and didn't fall all like the cashier told me that they would do. 
I tried to bring it to the owners attention and they told me that I needed to dispute them with my bank in order to get my money back, so I filed a dispute online with Chime only to receive an email stating that the investigation was completed and it was determined that an error didn't occur and I won't be getting my money back. 
I requested the documentation used to determine their verdict. because obviously there is a gap or something missing in their process because all three transactions were an error. I was rung up 4 times for cigarettes and only received one pack, therefore the other three transactions are considered errors. 
The clerk did not give me the cigarettes because her system showed declined so the cigarettes went back on shelf because it was believed that they weren't paid for and I left empty handed. 
When the documentation came back that the three transactions were settled I was shocked, something is not right, the store should have been out of balance. 
Since I was charged for something that I didn't receive should be considered an ERROR therefore I want the {$30.00} credited back to my account. 

Feel free to contact me if you have any questions ( XXXX ) XXXX Thank you, XXXX XXXX