Melvin's employee told us to use free wifi when we reach the door and contact her and she was there in few minutes. Everything went smooth on arrival. The flat is at the attic and might have a feel it is a bit smaller than it actually is because of the low roof but we had enough of space for all we needed and we were pretty happy with the place. The flat was clean with fresh sheets and plenty of fresh towels. Place had an airconditioning as described which proved to be very important when in Madrid during summer as it reached 40C during day.
Furthermore, I would like to point out that the neighbourhood is really great! Flat is located central and it is close to everything. Within 20 minutes you can reach most of the touristic places.
Finally, I would recommend using Melvin's place.