I used Pizza Hut all the time when I lived in Kissimmee. They have the online ordering and I never got a wrong pizza.
They don't have it here and there is a local pizza place near me that is great so I haven't use a Pizza Hut where I am now.
I have only once had a problem with a Pizza Hut and that was when I lived in Tallahassee. I asked for the manager and suddenly the meal was comped, I got coupons for free pizza for the next time I came and an apology. I have found asking for the manager in resturants usually brings results. The waiters and waitresses have very little control on how long things take and often get just as frustrated because it is thier tip that disappears when the people in the kitchen mess up.
I would right the letter. The home offices often like to know when a franchise, or even worse, a company store, it not performing up to par.