Yesterday I sold an item. Today it was collected. The seller provided me a QR code and a collection code.
The collection code didn't work.
An eBay representative claimed I was given the "wrong" collection code. It was different to the one she had, and asked me to contact the seller.
I decoded the QR code in the photo I took and it has both the item number and the collection code embedded in the link. So wasn't a QR coded or collection code for another item.
So, even if you do get a collection code, don't be too confident it will work.