under the EU directive u r entitled to some form of compensation if as u said they cancelled the flight with out any notice.. but with the airline(s) involved r nationals of non EU countries you might find/have difficulties in getting compensation from them in form of money.
best bet is to write to Atlas Blue head office and tell them the situation and keep a copy for yourself and also copy all your expences that you had to spend out on, and see what they do.
some airlines out of good will will give u the money back and that will be all...
good luck.