This could be invite only, so check your mail!
"With fantastic deals on eBay this weekend, it’s the perfect time to spend Nectar points. Simply convert your points to eBay vouchers by 23 November, and we’ll give you back 50% of the points you converted."
They had this deal a while back and it appears to be back again from the email I've just had
Step 1 : Make sure you’ve linked your eBay and Nectar accounts on My eBay – then set up your eBay account to spend points
Step 2 : Convert your Nectar points to eBay vouchers in multiples of 500 points.
Step 3: Spend your eBay vouchers on transactions of £10 or more.
*Until 23 November. 50% of Nectar points converted, up to a total maximum of 10,000 Nectar points (maximum amount of points credited back per user under this promotion) will be credited to eBay user’s Nectar account by 19/12/2014. Terms & Conditions apply. http://pages.ebay.co.uk/nectar-rewards/bonusfull-tncs.html