I agree with others who said you should've contacted the manager at the time of the meal. You said you chalked it up to a bad meal, but that's precisely why you should've spoken up at the time. The manager could have done something for you then, and it would also have given him/her a chance to correct any problems they might be having in the kitchen.

In the meantime, I would contact the mananger-on-duty at the Strongsville retaurant. I don't know how long it takes PFB letters to reach corporations (and how long it takes corportations to contact individual branches), but if this were me, I'd want to make it didn't happen to anyone else.