We strongly recommend Balta and his place.
Balta was kind enough to wait for us until past midnight since we had a very late arrival to Madrid. When we had a minor issue with the washer he arranged for his sister to come and take a look at it - all within an hr (this despite the fact that he was out of town)
The apartment is very well located. With metro and buses connecting to all major parts of the city, we hardly used the car.
The free parking was definitely an add on.
We will be happy to rent again