I stayed at Helena’s place with some friends just for a quick escape in Madrid and I recommend it as although the flat is a bit small there’s everything you need (even the bidet) and the location is really good! It’s just in front of the S. Miguel Market and Plaza Mayor, Puerta del Sol and Palacio Real are within (short) walking distance. The sofa bed makes the dining room area a bit tiny but that’s okay if you don’t plan to stay at home for long. The flat was very clean and quiet so we slept very well at night.
Helena was very kind as she allowed us to leave our bags there in case we arrived earlier than check-in time and she helped us when we had a problem with a flight cancellation due to a strike. We had just an issue with water the first day as it was cold and came out very slowly but Helena has quickly solved everything!
Recommended for a trip to Madrid!