Help on how to proceed

Okay so I've been following all the information I've received on this forum on how to deal with unlicensed lenders and so far I've been doing very well, and have settled 3 of them. However I am having some trouble with MyPayDayLoan. I took out a loan with them a few months ago for $400 and have paid $360 in fees so far, so I wrote them a letter and told them I was willing to pay the remaining amount of $40. I received a reply today informing me that I owe a balance of $520 and they will turn over to collections if I do not pay. I wrote them back stating it was a unlicensed loan and I do not owe anything more but principle and will not pay anything more then this, I've asked twice for a mailing address or MoneyGram instructions to send this payment and they only keep responding with how I owe for the whole thing since I signed their contract. Do I just ignore them at this point? I've already notified my employer and bank and both are willing to work with me if they try to withdrawal from my account.