Affiliates, PPA and the FSA

Hi, I'm in a bit of tricky position, I wish to disengage from a pay-per-lead model with which we pay our affiiates and offer them a PPA model, with further payments available if a customer sets up a direct debit. This should cut out fraud and hopefully give our top affilates the nudge to push upsells more at source. However, my rather rudimentary understanding of FSA regs and recommendations leads me to believe that I need to inform the customer of payments made to third parties during the process and before they click "buy".

I've done some scouting around and have seen that some banks and insurance services offer transparent incentives to affiliates on a per sale basis but nowhere have I seen a sliding scale implemented and I'm not aware if the customer needs to be informed of these payments anyway. Can anyone advise please?