Was this originally a collection item? Then, the seller has to either come collect it themselves, or organise a courier to come and collect .
What you must do is to open a return case for item not as described, I'm presuming this is a faulty item or not as described, and the seller then has 3 days to accept it pay the return tracked postage label, or organise that collection. if they don't you escalate the case on day 4, eBay step in and force the refund.
Whatever the seller says or promises, Do Not close the case early, and do not forget to escalate.
@lorrsm-84