Had a great stay in Carmen and Ignacios apartment. They live in the apartment, and rent out 3 rooms.
The apartment is central and in walking distance to eveything and the apartment was clean enough as well. They have a dog in the apartment which can say "Ig-na-ci-ooo". I found that super funny.
Only bad thing; the room was next to a noisy street and the apartment was not very soundproof - so bring earplugs if you want to stay there!