Im a bit confused as to what you mean by the T shamed you\this alter. do you mean the T called names, stated put downs (calling the alter negative and discriminating things)...

if this is what you mean the solution is contacting your locations mental health ethics board and the treatment providers supervisor. this T will be put under investigation by the state board. if the board finds that this treatment provider did do these breaches of ethics they will be consequences.

on the other hand if by ...shamed... you mean the T told you/the alter that their behavior was not allowed and set some boundaries and used a non nonsense tone of voice when this alter was acting out against the treatment provider, which resulted in the alter feeling put in their place and ashamed of their own behavior thats a good thing. may not feel like it right now but sometimes the best way to get an unruly possibly emotionally or physically abusive alter to understand whats expected of them and that they are not allowed to behave that way in therapy is if the treatment provider says and shows that by setting boundaries and making things clear with this alter he is not going to allow her to verbally abuse him, that she is welcome in therapy but like with anything else it comes with rules. She may not like these rules and what he says but this is how it is situation.

my point sometimes my own alters perceived my treatment providers to be horrible, and shaming them when all my treatment provider was doing was setting the tone and boundaries of what is expected in the therapy room.

also wanted to say that is amazing that you do have control when you want to. I never had that, wish I did, with me any time I got triggered by something my alters .....took....control. I could not stop or prevent them from doing so. they did so based on what their own sense of agency was.