Some business sellers are allowed to deduct up to 50% if the item is returned in a different condition. So, for example, if you had opened the packaging on a brand new item, they could make a deduction.
If you feel they have deducted more than was fair, you can contact Ebay Customer Services and see if they can help.
Use the link below to get a callback.
https://www.ebay.co.uk/help/eua?id=5275&mkevt=1&mkpid
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)