BP Gas Station ripping off people when it comes to gas for what your paying for Novi, Michigan

I'm new to the reporting game but I can't let this BP Gas Station get away with this. My friends and I were on our way to get some grub and watch the game when were in need of gas. We stopped by the closest gas station and pumped the gas. 
My friends and I all noticed the gas meter when we started driving that the meter was much lower than it should have been for the cash we had given. We had just paid the same amount in Troy, MI at the great gas station on crossroads Maple rd and Livernois rd. There was a significant difference which is why I had to file this report and should be investigated.