Combined postage query

[52liz]

I'm confused! How does eBay work out fees if I refund seller for combined postage after they've paid. Will they regard this as lots of sales and charge 30p for each item? Do they take fees on the total amount paid before refund? Or after refund? 
Buyer  asked for combined postage, I agreed and asked them to let me know when they'd finished bidding so I could send revised invoice. They  won 4 items and paid without requesting combined postage but now they want it. Fine but as these are very low value items I could easily be very much out of pocket. 
Any advice welcome, thanks

[john1297576]

So long as buyer only makes one payment only one amountbof 30p will be charged.

When you refund the excess paid, you are only charged the net amount,as ebay refund a proportion of the selling fee. When you have done this look at how the refund is calculated and paid.

At the end of the day whether buyer pays a combined invoice, or pays all thepostage and you refund excess, you are no worse off.