When you post an item it is always wise to put the tracking onto the item in your sold section straight away.
When a dispute is opened you make sure that tracking is on the dispute.
Did you do that?. You should have won if it showed delivered.
This is how you contact CS but too late now
www.ebay.co.uk/help/eua?id=5275&mkevt=1&mkpid
Weekdays lines open between 8 a.m. and 10 p.m.
Weekends they open between 9 a.m. aand 6 p.m.
Good luck I hope you get your money.
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We are just ordinary members trying to help.