Change shipping method after sale

Question

Good evening, I put a book up for sale choosing tracked parcel shipping with Poste, €9. This evening I sold the book and the buyer also paid for shipping. When it came time to buy the label, I realized that with Bartolini the shipping cost would be lower (€5.22). Can I change the shipping method and save the buyer some money? Thanks in advance to anyone who helps me.

sabryvv · Accepted Answer

Right, thanks for the suggestion.