UPDATE>>>>>
Thanks for all of the comments.
I took a chance on the ebay ones - £14 for a pair - it's not like it's a structural part. Comparing the replacement with the OEM, when I opened the box, I thought 'these don't look the same at all', with a much slimmer damping tube, so I just replaced the one that had failed, and crikey, the tailgate virtually opens itself, ha ha. It's early days, so we'll have to see how it goes. It does look a bit strange with one very slim, against the chunkier VW original on the other side, but who the heck looks at that when opening up the boot - and I've got the other one to put on if it bothers me that much. Been on a couple of days now, and I'm a bit nervous when getting stuff in / out of the boot, in case the tailgate crashes down on my head, but that's probably a bit paranoid, ha ha
Very easy to install too - a doddle. These were from Struts Depot - see how it goes.....