Insurance won't cover other in-network doctors other than the ones they assign.

I have Anthem Blue Cross HMO select. I initially wanted to see another dentist (in network) beside the one they tell me I can. I didn't like that one and requested that I be able to go to another. They said they won't cover it because they have preferred providers that they assign you to. I also wanted to see another psychologist other than the one they told me I have to go to (also in network) because the pre-assigned one doesn't fit in my schedule and I found one that does (again, who also accepts Anthem Blue Cross). I feel like I'm trapped. I can't use/don't like the one's they're telling me to go to, and I won't be covered if go somewhere else.

Any advice?