ShiroKuro Ugh, I’m committed to two more lessons in July and two in August with him before my regular teacher comes back… I’ll have to figure out what to do but I don’t think it’s a good use of my time, or money, to have more lessons with him. :/
Is it possible for you to switch to another sub? The current guy may be a good teacher for some, but given what you want to work on, it seems clear that he's a bad match for you.
I will say that I've never met a piano teacher who couldn't easily sight read anything I put in front of them, including pieces that are far, far above my playing level - I assumed it was a basic requirement for a teaching certificate from most schools. (One of my cousins is a concert violinist, and she can sight read piano pieces that are way over my head. She said that it's just part and parcel of the degree - that most music (or maybe just violin?) majors above a certain level are required to have significant fluency on the piano.) So I might let the school know that they might want to be more careful about placements with this teacher, since he's missing a major skill in the standard toolbox.
If you can't switch to another sub, or get a refund, perhaps you could ask the current sub what he's good at teaching. I wouldn't like to go down that path, myself, but if you can't get your money back, maybe it's better to not try to wring something out of this guy that he doesn't have to give. Maybe he could teach you some improvisation, or do ear training, or composition, or...?