This. My sense is that most schools try very hard to integrate day and boarding students. @skieurope often posts that the only difference between them is where they lay their heads at night. Clearly, this is not the OP’s child’s case, and I’m very sorry to hear that. There have been some good suggestions upthread, and I’m glad that the rest of the student’s experience at this school is positive, but it does seem like the school itself has some work to do and needs to be made aware of specifics.
I wonder if the OP is comfortable naming the school, perhaps current parents and students at that school would chime in (or PM) and maybe assist the OP in making valid concerns known.