Those forms said Mr Lynch had to pay a “Broker’s Fee” of $210...

Those forms said Mr Lynch had to pay a “Broker’s Fee” of $210 each time he received $600. The brokerage fee was 35% of the amount he received. - See more at: http://www.mauriceblackburn.com.au/...ss-action-in-queensland/#sthash.q5h8FqEZ.dpuf

The class action used Mr Lynch's example to conclude the annual interest rate was 160%. Mr Lynch's loan term should be 3 months or so instead of one month. We can reasonably assume Maurice Blackburn used a very typical loan if not the worst case loan. If you want to build a reasonable model, you might need to use 3 month 600$ loan as a typical loan, instead of imagining each month old loan get paid or new loan get applied.

I seriously doubt the brokerage fee is fixed. I doubt anybody was dumb enough to pay 210$ to borrow just 100 bucks