UPDATE 21 September 2010: No further action required - both Mina and my Facebook accounts have been reinstated. Thanks for all your help on this!
Just to send you all a huge thank you for your help on this. Facebook has written to me apologising for the inconvenience and reinstating my account. There wasn't much explanation given other than some general recommendations, which don't really apply to me. I have written asking for clarification on why this happened. I haven't returned to Facebook though because Mina's account has still not been reinstated. I'll only come back when she does.
Thanks again. Will keep you posted.