Julia, I think you need to spend some more time considering MMC's analysis and hopefully some more significant changes to how you present and market the costs of these loans.

I had never heard of 'flat rate' vs 'declining balance' interest rates. As far as I'm concerned, it's abusing the word to call your fees an 'interest rate' because they are not. They lack the necessary property of a 'interest rate', that is, being based on balance over time. What you are charging is a fee, based on the starting balance and period. I think you should stop calling this an interest rate, and I'd be surprised if it's not illegal to do this anyway.

It sounds like your 'service fee' is ALSO a flat rate fee based on the starting balance and period, which makes splitting it out and consistently footnoting it in your marketing seem deliberately misleading. The reason we insist on APR is because you can't hide anything from it. When lenders make up terms and market them, it's almost invariably because they are trying to hide costs. Somehow this cost hiding is always couched as 'better for the borrower'.

The "it's only 63 cents" trick won't work with this crowd. Because we understand how "interest rates" are supposed to work. If it's just 63 cents, then easier to refund it than write the blog post. But 5% of $2m is $100,000 so lets get real.

MMC includes a screenshot showing 'About this Loan' a few times during the article;

  Amount Requested:      USD 50.00
  Repayment Period:      6 weeks
  Grace Period:          1 week
  Offered Interest Rate: 25.00%
  Service Fee:           5.00%
  One-Time Reg Fee:      USD 11.78

  Total Amount (Including
  Interest and Transaction   USD 51.73 (30.00%)
  Fee) to be Repaid:

It was confusing to me, even with the explanation in parenthesis, that the 'Total Amount' did not actually include all the fees. You should call it a 'Partial Amount' if you want to leave parts of the total amount out. Otherwise, it should actually be, you know, the total amount.

If you can get users to pay the 'Registration Fee' completely independently of getting a loan, then by all means, have them pay it separately, and keep it out of the loan statement. But, what I imagine really happens is, users pay this fee to get a loan, then it's a loan fee, and you have to include it when you do things like report your total loan costs!