I have only looked at a couple of your current listings, but both offer 30 day returns.
If you offer returns (which being registered as a private seller you don't have to), you have to accept returns - for any reason, including a change of mind. Including the original postage, but not the cost or returning it.
Be thankful that they're not lyiing to get a free return by claiming it's not as described.
If you refuse, as this will be contrary to your returns policy, if the buyer uses eBay's money back guarantee eBay will enforce the refund.