Hey Ellen,
do a search on Paradise and I think you will see this issue raised a load of times. I have spoken to Stephen about this often as well and now have simply given up trying. We were the same as you… pre-affiliate program we also did the CPA thing with them and averaged something around 10 players a month. Now we have sent them 3 or 4 new players since the switch… I highly doubt that and nobody can ever convince me that something other than their stats is the cause for this.
Also, there are far too many affiliates also moaning about this for them to really still believe that their stats are fine.
I spoke with Stephen in Amsterdam about this and emailed a few times after that and still no change.. I have given up on them completely now.