Firstly would have referred your customer to your returns tab;

Contact must be made within 7 days of receipt of item(s) no extensions will be accepted in any circumstances. Before we will accept any refunds buyer must accept to provide adequate information as requested Eg. Pictures of the item and all posting material included such as packaging must be kept or photographed for claims. Item(s) must be returned in its original "BRAND NEW" condition "UNUSED" with all tags attached. Buyer must accept to bare the cost to return the item by “REGISTERED POST” only and pack the item in it's original condition. We will only issue refunds once the item has been received in its original "BRAND NEW" condition "UNUSED" with all tags attached. All funds will be refunded by whichever way the buyer has paid by. Eg. buyer pays with paypal refund will be refunded by paypal. All refunds are only for the value of the item. Does NOT included postage. Buyer must accept and agree to our Refund Policy to be able to eligible for any exchange or refund Change of mind Refunds Buyer must accept a cancel transaction within 7 days which will be sent through ebay or Final Value Fee (FVF) will be deducted from the refund amount after 7 days and refund processed.

I would have then asked the customer to advise why are they wanting to exchange the item & if needed ask the customer to take a photo of the item.

As a seller, it's important to keep the customer happy even in this case where they may have damaged it.

Up to you & if you have the same item, I would post the customer another one and just wear the cost. Its all about "utmost good faith", & keeping your customers happy.

I would also email and send a copy with the parcel & also contact the customer, that the customer will not be able to make any further exchange or refund on this item. Also ensure the customer that you have checked that there is nothing wrong with this item and apologise to the customer. It may not be your fault but dont make a fuss.

Just make a note of the buyer if they decide to buy from you again.

Good Luck 🙂