[Your address and contact number]
[Reference: Goods purchased through eBay on dd/mm/yy]
On [date], I bought [item] from you for £[xx].
However, when [item] was received on [date] I discovered that it was damaged in the following way: [details of damage].
The condition of the item was your responsibility up to the point I received it and accordingly I am entitled to [a refund along with a refund of all delivery costs/a replacement].
I would request that you confirm in the next three working days that you will provide this remedy and that you will cover the cost of the defective item being returned to you. Should I not receive this confirmation I will have no alternative but to raise a dispute through the eBay Money Back Guarantee dispute resolution process.
I look forward to hearing from you within 14 days of the date of this letter.