Many sellers here want the BUYER to pay the PP fees. You can alert him to the fact that the ad did not specify this, but I’ll bet he will still want you to pay. If the amount is significant and you really want the item, offer to split the fee with him.
But, since you've made a payment, I believe the seller has all the power in this transaction.
But, since you've made a payment, I believe the seller has all the power in this transaction.