Now they've paid you can make a partial refund this way, and use a laptop / PC preferably not the app or mobile browser it may not be possible there.
Click on the sold item, top left click on View Order details.
Far right from More Actions select ' Refund this Item'.
Then be very careful to add the amount you wish to refund into the box, or you will refund the whole amount.
Check it is correct, do NOT click on reset and send.
@mcdcrasheraqu6