Hey mattuk, I know it is hard finding a place here in Madrid and can be frustrating, even seems impossible at times but RoomMadrid is EXPENSIVE and although I know some people here who have used it and it worked for them, at 100 Euros it should be your last choice.
Good thing they have a bit of competition, check out
www.welcometomadrid.org .
The guy who runs it is named Donald and he charges 30 Euros for the same service (I think).
Saludos,
jer...