Here is my 'GUESS' (I can not see it exactly, because we don't have the referral fee, since we use NATS)
I 'think' the guy/lady from ccbill meant, that referral sales are the payments 'given' to the affiliates. However, when you cover their billing fees, those will be deducted from YOU as well...You can set the billing costs as, all costs for you, all costs for affiliate, or split the costs...
Or did I misunderstood your question?