Wow! That is a lot of helpful feedback and advice, thank you all. I have emailed ebay, responded to paypal and also rang paypal yesterday.

ebay's advice was this:

"Thanks for contacting eBay.I personally think it is a bit strange for a satisfied buyer who has received the item to go for a Paypal unauthorized credit card claim.

What I can do is to explain further what a Paypal Hold is.

 Payment Holds for eBay items is a joint feature in which eBay notifies PayPal of possible high risk listings when a PayPal transaction is completed for the listing.

PayPal may release the Payment Hold when one of the criteria is met:

 - The buyer leaves positive feedback after receiving the item."

When I rang Paypal yesterday I quoted what ebay had emailed to me and asked if it was true, and the Paypal guy on the line said he would make a note in the file that the buyer had left positive feedback. He wouldn't say one way or the other if the positive feedback would make a difference to my case, just that he would make a note.