Just checking that you are running stock, right, not Fission as you have that in your sig?
If you are going in to the store, then yes, unfreeze and unroot. You are allowed to download non-market apps anyway, but if they are apps that clearly need root (in the name) uninstall them for now.
However, I don't really hold out high hopes that you will get good info. Now that you are back, the problem cannot be reproduced, and anyway, you were using Orange, so I'm pretty sure you will be told that next time you should contact them!
Hopefully I will be proved wrong.
What others have done in a similar situation (while abroad) is to try a SIM from another provider. (Borrow from a friend, buy the cheapest). And sometimes that seems to work, because of some incompatibility between one providers SIMs and the phone.