If I am not mistaken I think you are talking about an accommodation finding agency that has a few of it's own properties, which is called Room Madrid / Room Europe.
The only problem with them is that they overcharge you for both the rent and service fee.
Room Madrid, just like Sal y Ven, AccomMadrid, and all of the other similar agencies are stuck in the old mode of re-renting all of the same flats from all of the same landlords in Madrid, who keep raising their prices and lowering their quality of service.
Now there are two better options which you can use either both, one or the other.
First there are the short term rooms ypu can rent for one week minimum stays through the Madrid Insider: Booking Dept.
These are single rooms for 15 euros a night or double rooms starting at 20 euros a night. See
http://www.madridinsider.comThis gives you a chance to get to Madrid and have a place to stay short term while you conduct your longer term housing search.
Next, there is the phone calling and appointment setting services offered by Donald Timson at Opening Doors.
For his 50 euros or so service fee, he will call around Madrid for you and set up the viewings so that you can just go look at places until you settle on something that you like. He spends a lot of time calling the landlords and sending people on viewings so he has a better feel for what is available than someone just picking up the Segundamano newspaper and trying in for themselves.
I would suggest:
1). Take a place for one to two weeks through Madrid Insider: Booking Service
2). Try to find a place on your own for a few days (Segundamano, In Madrid, internet search, bilboards, new friends, etc.)
and then if you have no luck with it and get frustrated...
3). Contact Donald Timson at Opening Doors.