Disputing missing cashback for a purchase

[ilya980]

Hi,

Is there any way to dispute a missing cashback that was denied by a merchant's affiliate?

I made a purchase using a link posted on a well-known cashback site. The click was properly recorded. The purchase was made, I received the order confirmation email 4 minutes later, and then the item was shipped and received. The cashback promised by the cashback site was denied by the merchant. The cashback site support says that the merchant denied them the commission for this transaction because it was paid to another affiliate. I have no idea who another affiliate could possibly be. The merchant would not say it. The merchant's customer support says that the affiliate I used for this purchase needs to contact the merchant's corporate office. The affiliate says that they contacted the office and the reason the denied commission was because it was paid to another affiliate. 

Is there any way I can get the cashback? 

Thanks.