Was this a state-run treatment center? Because you can write your state rep. about it and get a chance at having your voice heard by someone who can actually do something about it.
If it's private I'm sure there's still a head-honcho you can write if you google the specific treatment center.
If it's a popular treatment center you can even write a review about your experience and what you've witnessed online.
I wonder what they mean by "it is inappropriate to get upset or angry over names and dress codes." I'm not trans but I don't like my name so I go by another name and this has never been an issue at hospitals/treatment centers for me, so why should it be different for anyone else cis or trans? I get them having a dress code, but why would that affect trans-people more than anyone else unless they don't allow certain people to wear clothes that are acceptable for other patients of the same gender but opposite sex.
(Sorry if I worded anything in an offensive manner, I'm not very familiar with how to word things when it comes to transgender things, just let me know a better way so I can learn).