Expedia Special fares on some BA flights - cheaper than ba.com

Has anyone else been presented with this from Expedia? I found a holiday for myself, wife and 2 friends, selected in on Expedia at the advertised price (£370.00pp) plus £26.00 each extra for a more convenient flight schedule, and when I went to pay I was told on the payment screen that the price had gone up by £16.00pp. Not wanting to loose the holiday and disappoint our friends - I accepted and paid. I then asked Expedia why on 3 occasions and they said its down to whatever the hotel want to charge and accepted no responsibility for that. I pointed out that they had offered a holiday at a price and at no time does it tell you the price is a "guideline" price. I thought this practise of seducing you with one price and then charging more was stamped out - but clearly its not. There is little transparency here - Expedia staff just stand firm and basically say "tough" or "you accepted the price so there is no recourse". So was I supposed to try and phone them when I saw that message and risk loosing the holiday - I think not.
So BEWARE of EXPEDIA'S methods.