There will be no point in contacting eBay. Their own money back guarantee only lasts for 30 days. After that, eBay has no interest - it's between you and the seller.
If you paid or funded the payment from a debit or credit card there's a chance your card issuer may be able to help.
Otherwise, if your seller was a UK regisered businesseller you may have some statutory consumer rights. There is plenty of information online, or consult Citizens Advice.
Unfortunately, having rights is one thing - being able to enforce them against distant eBay sellers who don't want to know may be another. The reality is that the uncertainty and possible cost of legal action seldom makes this worthwhile for most items bought on eBay.
