Full House Chinese Restaurant secret "service Charge" added to bill Kissimmee Florida

My family went on vacation this past week to Disney. We ate at this restaurant. It has an all you can eat buffet, which we had. When the bill came , we noticed a charge of $9.60 to the total...with the letters S.C. next to it. We asked the waitress what the charge was and she ignored our questions. We left a tip on the table, and went up to pay the bill. When I asked what the charge was for the person at the cash register told us that it was a service charge that they add on because "the tourist don't tip". I asked my son to go back to the table to retrieve the tip money that was left. He came back and said that the waitress had picked up the tip money. I told the cashier that this practice was not legal and that we woulld not pay his service charge.we deducted the service charge and paid the remainder of the bill and the cashier did not argue.

Honest engines
whitewater, Wisconsin
U.S.A.