To guarantee a refund for a faulty item if received within 30 days of the item's last estimated date for delivery, you have to open a case for item not as described, citing item Does Not Match Description or Photos. Did you do this?
If not, then there is nothing to enforce the seller to refund you.
If you are in time and sent the item tracked , open the case now, enter the tracking number, after it shows delivery if not refunded within 48 hours, escalate the case, eBay step in and force the refund.
eBay's 30 day MBG Money Back Guarantee is written on every listing and on the link below, worth reading so you don't lose any money in the future if this happens again.
https://pages.ebay.co.uk/ebay-money-back-guarantee/
@mcb284