The listings state the combined shipping criteria that the seller and buyer must abide.
You've requested an invoice or total from your purchase page? If not, do so.
I wouldn't pay until the items are invoiced correctly.
Give it a couple of days.
If the seller still doesn't remit, contact eBay and advise them of the situation, and that you'll pay promptly for the items when the S&H is adjusted as described, otherwise you'd like to cancel the transaction.
I've been in the same situation and this resolved it.