I want to make a formal complaint to Dominos (Pizza)?

Recently I was sent a pizza which had some tuna on it, which I cant stand. I ordered a pepperoni pizza and what disgraced when eating tuna! Which made me nearly puke! Then I I ordered a pizza tonight and the pizza had a bit of tandoori chicken, which I don't mind but I ordered a pepperoni pizza! And as it was two for tuesday I got another one which came as a cheese and tomato pizza with no stuff crust and I choose pepperoni again! I was going to save it till the weekend but the pizza has no toppings and is not to my liking. Ive complained once and got a new pizza but this is getting ridiculous. *was