Customer requests upgrade to prior mail after processing

[cindykayboutique]

my customer sent me a message asking if I would upgrade shipping to priority mail and she would pay difference. I thought she could choose priority, however, she paid for the 1st class shipping. Now I want to send her an invoice for the difference and there is no invoice option. I've tried all the methods I have read on Seller Hub.

[comics-scifi-collectibles]

@cindykayboutique  Two ways to handle this...  you can cancel the sale as buyer requested, refund the buyer, relist with the Priority Shipping.

OR  You can share your email address since you have a recent sale together and have them send the funds to you electronically use Venmo or other payment transfer method to pay to ship the item again.

This is not considered an offsite sale since the sale already took place.  

Before you do either of the above I recommend looking up the Priority shipping cost and quoting them the difference as they might change their minds.   https://www.ebay.com/shp/Calculator