Sorry, for the late reply I have just seen this question is unanswered so if solved please ignore !
The best way forward is to cancel the order with the buyer's permission, and relist when the buyer is able to receive the item. You cancel citing ' Buyer Requests to Cancel', this fully refunds them, and your seller performance is not affected.
For the unused postage label:
- If you selected 'Buyer pays’ when you created the listing, your buyer will automatically be refunded for any Simple Delivery label that isn’t used after 30 days
- If you selected ‘Seller pays’ and offered free postage on your listing, you'll need to fill out the Request a refund for Simple Delivery form for the label that wasn’t used. Make sure to send your request within 14 days of your item selling. Also ensure you add the replacement tracking number of the service used, and it shows delivery.
@bigcups22