Hi DayDay,
I've had the same problem, moved into a new flat with a Sime Boiler but no manual. I've contacted the Sime customer service through their website
http://portale.sime.it/wps/portal/uk
and they sent me the manual as a pdf on the next day (!!)
If you don't get a response from them pls post here again and I can email you the file, if you want.
Best
DeeDee
DeeDee, January 2009