Have you ever run into a store with a sign posted that states they charge a fee for any purchases under a certain price if you pay with a credit card? Card Card companies have restrictions on when a fee can be charged. No fee is allowed for amounts greater than $1. If you come across a store that is charging a fee for any amount greater than $1, just leave and tell them why you are leaving. If you are a regular customer, perhaps gently remind them of this before you take off.
Then, report that place of business to your credit card companies. They will take it from there.