Tiger Stop Exxon Charging for Premium gas when Regular was selected. 88 cents difference a gallon Pearland, Texas

I stop at the corner Exxon station to get gas. I used my Exxon credit card and selected the Regular gas. The price changed from 2.09 to 1.719 and I filled up my SUV with 16 gallons of gas.  I noticed the price was over 40 dollars.  I always get a receipt and I looked at it to see what the issue was. I knew that 1.71 X 16 would be less that 30.00 dollars.

I noticed I was charged for Super premium.  I know what button I pushed and the price change on the selection.

I went to the clerk and he said I was mistaken and I put Super Premium in my tank.  I did not. I am frustrated that I even went to this station.  It was convienent but I will not be going back.  I have been there before and had a couple cents difference from the price shown but did not complain.  This was a $14.40 difference in price.