Was the seller registered as a business or a private seller (despite appearances you will need to check the original listing)
If it was from a seller registered as "private" (even if they are legally a business) then you won't be able to return it for "change of mind" as eBay doesn't force sellers registered as "private" to accept returns for change of mind.
You would need to take legal action outside eBay to force a seller registered as "private" to accept a change of mind return