Where to stay in Oaxaca December and January?

Hello, I will be in Oaxaca from mid-December to mid-January to study Spanish and am looking for someplace to stay, preferably in El Centro. I speak some Spanish and I've been to Oaxaca before but it was more than ten years ago. The school I'm registered with advertises help with accommodation, but it turned out the only help was an email from them saying "try airbnb". I'm not finding much on airbnb for my dates that isn't a fortune, and most of the cheaper hotels also seem to be full up for those dates. I'm not too picky but am hoping to find something clean, friendly and relatively quiet. Thanks in advance for any advice/recommendations!.

Try a hostel like Casa Angel, then look around on bulletin boards, also using word of mouth. Craiglist may have a lead.

I don't know where you are seeing that cheaper hotels are filled up during the time you are there but i had that problem when I called hotels in Mexico City. Then I went to Hotels dot com or one of those sites and had no problem getting a reservation even at hotels that I called 10 minutes before. Hope this helps.

Hey,
I stayed at a perfect little place owned by a beautiful woman in centro Oaxaca city. I was alone and felt very safe in her compound at night & was able to walk everywhere. It was a self contained unit with double bed, private bath & kitchenette. It was very reasonable & Susana Braga was a perfect hostess & very knowledgeable. I found her on Airbnb under Casa Sopetran in Oaxaca city & would definitely stay there again. Address is Matamoros 603, Oaxaca, Oaxaca 68000 Mexico. There are 300 reviews now so that should be helpful. I stayed with her in August of 2016 & my name is Tana. If she has availability I am sure you will love it & the location. Take care & good luck with your accommodation & studies in beautiful Oaxaca city.

so where did she go?