Of course, it's not certain. I said probably. There is a difference between FB giving a refund and a credit card dispute. The dispute may fail and they will be forced to pay , since the charges are technically legitimate. If Facebook simply refunds them, there is no chance of them paying. The rational thing for FB is to never refund them, take what you can get...
If that were certain, then it's irrational for facebook to refuse the refund.