Plain Green Loans Interest rate not legal Box Elder Montana

I had a loan with Plain Green Loans and the interest rate that they were charging is illegal in my state. I contacted my attorney Generals office and was told that they are not licensed to do business in the state of Washington and that their interest rate was higher than the legal usary rate in the state. My loan was for $2600 and the payment was $268 for 19 months. When I did the math I would be paying almost double the amount of the loan and that I had paid off the principal with my 10 payments. I wrote them an email requesting that they remove all my banking information from their records and if they wanted to contact me it was to be by mail only. I did get an email saying that they were a legal loan operation and that the state had no control over what they charged as they were an soviergn nation under the Rocky Boys Indian Nation. They claimed that only the United States government had legal jurisdiction over them. I put a stop payment with my bank on their withdrawals and have not paid any monies since. I do not feel that I cheated them as I had paid back the total amount plus that I was given. They have not contacted me since. I am a senior citizen and live on Social Security only. I hope this helps others who took out loans at higher than what is legal in your state.