Looking for a Spanish native speaker guide.... (Madrid)

I'm visiting Madrid with my partner for the the long weekend Protected content long in Poland anyway) and looking for a Spanish native speaking guide for a day long tour of Madrid on 20th, looking at the less well known side of town. Also because my partner is taking the opportunity to be immersed in Spanish language as preparation for her next week exams in Spanish Philology.
If anyone can recommend an experienced guide then it would be much appreciated.
Best regards,
Iain.