There is a new notice from Paypal that is the item described does not match the item sold the customer can file a complaint and you will pay the full refund plus shipping fees both ways.
Option 1- See if the customer will accept the item as is and a refund the difference in cost of the item. Best option
Option 2- Get the item returned and order the item they wanted. You pay for the return shipping.
Option 3- Get the item back and give a full refund.
There are no other options.