If the item has already sold, you cannot charge the buyer additional money.
If the listing is still active, you can try to revise it.
$4 is for international mail, not packages.
Look in the section of the listing for where you would input the weight & dimensions.
You would have 4 choices:
- Package/parcel/thick envelope
- Large package
- Large envelope
- Letter
Make sure you have selected one of the first two.
