Comics-scifi_collectibles Is a Volunteer Community Mentor.
@artiejay This is a setting on the sellers account. A buyer can not turn off auto pay.
Some sellers do not realize that eBay turns on the option to require a payment prior to making a bid or offer by default.
Sellers can uncheck the option in their account settings.
You could ask sellers prior to bidding if A ) they allow combined shipping and B) do they know if they have the payments required option before placing a bid auto checked by eBay as this makes combined shipping more difficult.
Sellers can still combine by refunding the difference but eBay can't force a seller to send a partial refund after a order is made. Most sellers will make a partial refund.
