That loan is almost double the APR maximum in Oklahoma.
Check that out, it’s got a full step by step for dealing with these loans.
One last thing to add.
Be prepared to be harassed for the rest of your life.
My family and I, even my brothers ex wife get calls threating to serve me papers at my place of work or residence. Of course they never come and in my case:
So there is no way they could collect but I guess I'm on a list that bounces around and around.
Unfortunately there really is nothing you can do to stop the illegal collection activity from these fly by night zombie debt purchasers from calling and harassing. Sure it's illegal but they can't be stopped as it bounces around and around and around. The good news is my credit report is clean of these but I did have Cashcall as a collection but it has long since been removed.
In no way am I suggesting you pay them back more than principal and even if you paid it per the origional terms you might still get those harassing calls at some point in the future. The calls are scary they sometimes know your social security number, employer, bank, dates of the loan....
You should consult an attorney or call the office of the AG for your state.
Tribal law vs state law considerations will require legal counsel to evaluate, and I would not rely upon any advice offered in a forum.