A number of auctioneers here got really upset that, after making thier bidders wait up to seven days to learn if they had won the auction, the seller might have to wait four days for the buyer to pay.
So eBay caved and instituted Autopay, which is a pain in the badonkadonk.
Among other problems, is the inability of the system to make combined shipping.
Anyway, contact your seller . Let them know the problem.
They can once all is completed, refund part of the shipping you are forced to pay.
