A "tortilla espanola" is potatoes cooked together with egg in a pie like thingy. It is quite normal to eat that for breakfast, especially second breakfast at around 11AM. It is ok for it to be cold unless you ask for a heated one, or it was just cooked. If you want a hot one, just ask to heat it.
In fact, I eat it for breakfast all the time :) Maybe yours was badly done, I can tell you that mine are excellent :D
Also, a fish fillet is something you get with specific fish - cod, salmon, tuna, swordfish. With a sardine or a dorada, I expect to be served a full fish.
