Discretionary service charge

I ate in a fancy restaurant today where the service was slow but polite enough. When it came time for the bill there was an extra charge at the bottom labelled discretionary service charge. Cheeky I thought, but ok.

I indicated that I was ready to pay and the server brought over the wireless payment terminal and I watched out of the corner of my eye as he entered in the details nearby. A question popped up asking if I would like to accept the discretionary service charge with three buttons, Yes, No, Other. He selected Yes then handed the terminal to me.

Now he assumed that I had not seen all this but I had and I was now somewhat annoyed. In the UK a discretionary service charge is one where the choice belongs to the customer not the server to decide.

What would you do if this happened to you?