You had a great meal but appalling service yet there was a 12.5% service charge added – do you pay it?

ok so it´s Friday, time for my question of the week…..
You go to a restaurant and you are really looking forward to the meal, the place comes highly rated so your expectations are high, and sure, it´s a little bit pricey but hey, you don´t mind paying for the quality.
You are aware that there is an additional service charge to be applied, 12.5%; Your meal that was fantastic but the service was appalling, would you ask for the service charge to be taken off your bill? Would you have the energy and the confidence to do this? Have you ever done this before? If so, we want to know – post your comments below!
Thanks