Keep trying to ACH the money from bank account

I live in MO and from what I can find, Kenwood Services is not a legal lender in MO. I borrowed $300 and have paid them $280.00. I sent in the letters stating that they are illegal in MO and that all I was responsible for was the principal. I also sent in the letters to Revoke ACH and Voluntary Wage Assignment. I told them I would pay the $20.00 if they gave me the address to where to send it. They did keep trying to ACH the money from my bank account but I closed it.So, now I got a letter from NCA saying that they purchased the Kenwood Account and that I owe $590.00.How do I approach this? Kenwood Services is not legal in my state.