i stayed in charos apartment with 2 of my friends (all university students on holiday) and i honestly cannot recommend it more.
we stayed in a room with a double bed and charo kindly popped a single bed in there for the third person. Connected to the bedroom was a small side room with a desk and mirror (which was perfect as a makeup / getting ready station), a mini fridge (which had some water and juice already popped in there) and a rack with towels. The entire accommodation was very clean and tidy.
Charo greeted us at arrival, gave us a tour of the flat and was incredibly helpful. She gave us lots of recommendations for the area and even circled potential spots on a map that we were given as well as messaging us a few links on whatsapp.
In the kitchen Charo left some breakfast bits (croissants, small cakes, pastries) which we had with coffee from the machine - this was fab and meant we could have a quick and free breakfast at home. we had access to the kitchen (but not the oven) which was great as we could make sandwiches for lunch.
the location is absolutely unbelievable, right in the center and there was millions to do around it. we travelled by foot the whole trip and had no need for public transport as the location was so close to everything you could possibly need from restaurants, clubs, cafes, tourist sites and shops
overall, absolutely wonderful flat with a very lovely and helpful host!!! i recommend it to anyone but especially young travellers looking to spend the whole day/night out in madrid and just need somewhere central to sleep and get ready. 10/10, will definitely stay there again!!