They haven't actually hacked my account, they are just giving out the address. I have changed password and security question as a precaution anyway. I've also checked my online banking and credit card - nothing suspicious.
So far they have bought some electronic stuff (TVs etc), booked a holiday, and requested items from a professional soccer club for a charity auction (!).
It could be someone with a very similar email address, but I have a feeling it's fraud of some kind.
Should I be worried? Is there anything else I can do? Should I try to communicate with the stores/people involved?