CITGO review: deceptive and rude service

My son and I went to this store to purchase fuel. I noticed immediately that prices weren't on most of the merchandise in the store and that they decide the prices when the customer gets to the counter. After giving the woman at the register money for the fuel, I awaited my change as my son began to pump the gas outside. The lady didn't set the fuel pump to stop at the price I was paying for and just assumed that my son knew to stop at a certain amount. After she realized that he was waiting on the pump to automatically stop, she then told me to tell him to stop pumping because she "accidentally" overset the amount. By this time he had already gone over by $4. She was holding my change and rudely told me that I "had" to pay for the overage because she made a mistake and couldn't stop the pump once she started it. She deducted the difference and threw my change to me. I was displeased that she knew she made the error (possibly intentional), and held my change without letting me know she didn't set the pump and was very rude and very unprofessional. To make matters worse, when I told her that it was her error and that she had no right to just take my money. She told me that I had to pay the overage because the pump went over and that she would write down my license plate and tell the police that I stole the gas if I had not paid the difference. When I asked for a manager she told me that he hardly ever comes around.
Rude, unprofessionsl, crooks who disrespect, deceive, and practice usuary on the people who shop at their store. Needless to say, I am one customer who will NEVER do business with these people again.