You can update the weight when you purchase the label, but you cannot pass those costs along to the buyer. This was not their mistake, and they do not have to pay for the difference in the shipping label.
There are no prepaid shipping labels on eBay, by the way. The buyer pays you the shipping cost you set in the listing, and then you purchase the shipping label using the money the buyer paid you.
Volunteer Community Mentor | Posting ID
