Thanks a lot for the quick reply, I thu9oght this would probably be the case! It's no massive problem but just doesn't look brilliant, but as long as it goes eventually!
The reason for putting the 'site down' message up was just because they really hated the old site (didn't look at all professional, not the kind of image they wanted to give), and had already given potential customers the address in anticipation of the new one.
But in hindsight, it would've probably been better left as it was!
Other than that I agree with you, not really much point to those messages at all.