I am always reading threads on various boards with members complaining about how so & so Merchant or CPA Network banned them and didn't pay for one reason or another. I know there are some shady programs out there but what is more likely is that these people probably did something that was against the TOS and deserved what they got.
Here is my advice I always give them.
This type of thing happens all the time. I have no way of knowing what you did, or if you were even doing anything wrong to deserve a ban, but this is something everyone should always be prepared for in the affiliate marketing game.
NEVER EVER, NEVER EVER, NEVER EVER keep all your eggs in only one basket. That basket could fall and there goes all your eggs!!
Always spread your traffic/earnings out over more than 1 affiliate network. Have a backup plan so you don't lose 100% of your earnings if you get banned by a network.
Chalk it up as a lesson learned and move on...