I just realised I quoted the wrong bit in my last post.... 

clarry - just to confirm, when you create your listings, in order to show the first option as free post, do you tick the "free postage" check box, or do you enter $0.00 in the postage cost field?

According the the eBay rep in the bit I meant to quote, the current workaround for this glitch is to have $0.00 entered into the field rather than free postage ticked (as I said, it shouldn't be necessary and even bulk editing can be a pain in the you-know-what, but if it works it's probably worth it).