I recall many years ago being in a restaurant in Cambridge, England with an English friend. We had deplorable service which we complained about. It didn't get any better. I was paying for the dinner, but when the bill came my friend grabbed it. When he saw that they added service charge, he called the waiter ant told him we were not paying the service charge. After arguing, my friend demanded to speak to the manager. The manager was trying to justify the service charge. Finally, my friend checked his wallet and found that he had change enough to pay the bill without the service charge. He handed it to the manager. When the manager protested, my friend said, "Call the police if you want, we will wait right here." He didn't call the police and we left. If that had been in the US, I would have handled it the same way. I was reluctant to make a fuss being a tourist there.