rose I can assure they DO NOT side with the buyer the moment a dispute is escalated to ebay.

I have a dispute that has been escalated to ebay and it will take a 7 to 10 days to decide the outcome even with photos that the item is not as described as the photos show completely different story to that of the description.

So buyers do have to fight for a dispute to be in their favour.

That is why I said the to OP to fight it as the item has been worn for several hours, it can not be returned in unworn unused condition so it is not in the condition it was sent,  the seller can not resell underwear that has been worn, the buyer has said they like the item but after several hours of wear it is not comfortable, that is not the fault of the seller.

So they can not go for item not as described and should not win