Contact the Consumer Financial Protection Bureau?
https://en.wikipedia.org/wiki/Consumer_Financial_Protection_...
Their homepage has a link on the top-right to submit a complaint.
It's possible your state government also has an institution for consumer protection in the finance sector. For example, there's the California Department of Financial Protection and Innovation.
https://en.wikipedia.org/wiki/California_Department_of_Finan...
Navbar at the top of their homepage has the link to file a complaint with them, if California is your state. If it's not, you can search "<your state> financial consumer protection" to find who's responsible for financial consumer protection in your jurisdiction.
I would try one of state or federal first, and not both at once, so they don't step on each other's toes. If one fails, I'd then consider reaching out to the other.