I am presuming they are a business and accept returns? If they are in China I think they will be.
Open an ebay return, using the most appropriate reason. Is it a £Not as described" return? If so use this as the reason for return,
Your seller will send you a prepaid return label with an address for THIS COUNTRY within 3 working days. If they don't you escalate to ebay on day 4 . Your seller will refund once they get it back, again if they dont you escalate your case again.
Your seller is trying to discourage you from returning your item by lying and telling you it has to go to China. If the listing says it is from the UK this is where you return it to, don't let them browbeat you, stick to the case and do not close it until you have received your refund.
