Debbiec,
Before you pay a dime to National Processing, you will definitely like to have your debt validated. You should know the proper calculation of how $100 loan can become $300.
If they are doing legitimate business, I hope they won't have problems in getting the debt validated as per their loan contract.
As you are willing to pay the debt, please do not get intimidated. They are trying to scare you so that you pay them with anything. If you do so out of scare, I am sure they will try to pull money in the future also. Get receipts after the debt is paid and ask them to update your file with the credit bureaus also.