If the seller is not being helpful then open a case for item not as described in the Resolution Centre, that, they cannot refuse or ignore.
https://resolutioncentre.ebay.co.uk
If they do not refund you in 3 days, escalate on day 4 and eBay force the refund.
If they want their item back first, they have to issue you within those 3 days, a pre paid tracked return label. Once they receive the item back, or eBay tell them it has been posted, theythen have 48 hours to refund you. Again, if they do not, then escalate the case.
Do not close the case early on any excuse or promise the seller may give, and do not forget to escalate.
