Hi rainonthewindow,
Thanks for sharing this additional information with us. We have just updated our eBay UK lister page to support these new options, so you should now see two additional drop down menus labeled "Item must be returned within" and "Return shipping will be paid by" when you specify that you will accept returns while listing through Auctiva.
If you encounter any difficulties when using these new options, please don't hesitate to contact our Customer Support team by mousing over the “Help” tab and selecting the “File Support Case” option.
-Mike