elrao - that sounds absolutely rotten. Not the start you want for a holiday.
FWIW, even with your young kids it might be worth looking at doing EI from DUB in future. You get the pre-clearance, the product in Y is perfectly fine (or so I'm told by friends with families who do an annual MCO trip) and even though you won't get TPs or use your silver card, you will still get Avios off it.
Alternatively, my friends also recommend Virgin from LGW (one's just moved his business over there after a couple of low par BA flights too many).
Hope you get something from your complaint, but from what people here are saying I wouldn't hold your breath.
1F