I need help with a letter

I just received this today in my email: Oh and to let you know, I've already paid $35 on this and only owe them $55 since they are an internet based pdl and they are illegal in the state of Iowa. Now my question is this. What type of letter/email can I send back to them that states the Iowa laws and that I've already paid x amount of money and only owe them x amount? Can someone help me and show me the right form. I've tried looking over in the Do It Yourself section but couldn't find it and I can swear that I've seen it before just can't remember if it was a post or in that section. Thanks much for all your help!

Dear _______________,
Your loan is past due!

Loan Shop Online provided you with a $100.00 loan on 07/29/2009. I would like to discuss the options available for you to pay off your account. Your current balance including principal and fees is $115.00.

What can I do to help you meet this obligation?

Please contact me at 1-888-265-5074 about account number ____________.

The sooner you call to discuss your account, the sooner your account can be paid in full!