Thanks and I did look at that

Unfortunately the option to change the package size didn’t appear for me after the sale had completed - and cancelling a sale is madness when I'M paying the postage (i.e. offering free delivery) 

My issue is Simple Delivery now prioritises eBay’s convenience over seller flexibility. It may suit some occasional sellers but it just creates problems: I've lost control over postage choices, and, as I've found - can’t adjust package sizes easily after sale. This, plus combined postage is now near impossible, and you’re pushed into using eBay’s carriers rather than using the most suitable service yourself.

It also feels like another way for eBay to keep the entire transaction inside their system: listing, payment, postage and disputes gives sellers less independence.

The old system wasn’t perfect, but at least I had control over how I shipped my own items!