The syllabus is basically a semester-long contract between the prof and the students. Yes, it is subject to change but not without advanced notice. This prof sounds like he is reneging on the contract. You are paying for the class (or someone is). You have every right to speak to an advisor, or whomever else can do something about the issue. At this point in the semester, I don't know that there is much they can do--I had an issue a few years ago in a trig class where we went through 3 profs in 3 weeks, one didn't even show up for class and the grad assistant taught for two classes. It was a cluster; I'm terrible at math, and the differences in teaching styles/methods made it impossible for someone like me to follow along. I dropped the class during midterms because I was so behind I couldn't catch up. I sent a letter to the head of the math department and the dean, and they were basically like, "Yeah, we know. Sorry. Here's your Incomplete." But you should still talk to someone.

The prof is allowed to miss class once, even twice--they get sick days, too. But there should be make-up work offered or notes posted. And not responding to communication is just lazy and unprofessional.

PS I just graduated and if any of my profs had behaved this way, my entire cohort would have been in the director's office so fast...