Final Update, the Original Seller offered me a refund excluding postage, without requiring the bonnet back, so it would have stood me at £60, plus I still owed my buyer £50 for the insured return postage, so I could sell the bonnet as defective to cover those costs, but I didn't wanna take chances, so I requested a full refund, and they agreed, I got that today, but then a slight twist...
I was credited, I had the defective bonnet, and still owed my buyer his £50
so I stuck it on the bay at what I thought was a reasonable if not pricey £125+ p&p (of £50) and had some interest, the successful ebay sale at this price would have given me ~£40 for the overall inconvenience
I was offered an acceptable £100 cash on collection and provisionally accepted, now, I don't take things off ebay until the deal is done, so I upped the price by quite a chunk, pending payment from the cash offer i'd had, and while still waiting for a response on that one, someone only pressed buy it now and gave me £225 including postage, thus leaving me £125 up!!! result
in all honesty, I advertised it as accurately as I could, and had I been a buyer, I wouldn't have bought it at the price it went for, but i've covered all bases on it, all defects were mentioned, and it was listed as for parts or not working, no returns, and i'm a private seller, and the chap who bought it is sticking it on a drift car, which implies its gonna get knocked about from time to time anyway