Seems like an abuse to me. Clinical trials benefit laboratories that must test their drugs before putting them on the market, these laboratories must assume all expenses, even in some cases they should compensate those who participate as volunteers in the trial for the risks they assume.

The billing department might not know you are on a trial and should not be charged. I’m on a trial. my research coordinator has had to contact billing a couple times when I’ve been billed for research visits.

Yes, look at your paperwork from when you entered the trial, and speak with the billing office where the trial is being conducted.

Take notes, and good luck.

You may be able to appeal the charges.

I would assume not
It all depends upon what you agreed upon when signing up
Good luck