Let me put the 20% rule that you illegally implemented in a different perspective.
Let’s suppose an affiliate is starting out in the business, and manages to get you a few players right away – but after a few months, he/she happens to have a month where one or more of the following things happens:
1. The site is down for an extended period of time
2. His/her newsletters are unwittingly blocked by a spam filter
3. He/she can’t compete in the PPC price wars
4. The tracking system fails or is otherwise manipulated, internally or externally
5. NOTHING AT ALL HAPPENS, except that for whatever reason, the affiliate doesn’t get a signup that month.
You’re going to penalize him/her for something that isn’t within his/her control, despite the fact that he/she has your banners up in good faith? What’s more, you’re going to deduct what he/she has been promised in the contract for the lifetime of the player?
Get real.