Many buyers are experiencing problems trying to get combined postage discounts from combined invoices. There are two main problems that eBay has not fixed yet that cause this to happen:
1) You can’t request or pay for combined invoices via the eBay phone app. They have not made multibuys a feature on it yet!!! So do not use your phone to buy if you want combined postage/shipping discounts, use a pc or laptop or use the classic site.
2) Using shopping cart on a pc or laptop, you can’t access multibuys if you purchase from a different eBay site. The solution is to login to eBay.com.au before you buy multiple items from us and it will work this way… Or better still, don't use shopping cart at all, and buy them the old way by committing to buy without paying straight away, and “request a total from the seller”.