Seller indicated international shipping available and responded positively to shipping with USPS. After my commitment to purchase item without clearly stated international shipping, a request was made for an updated invoice to reflect shipping to my country.
Within 2 days, an updated invoice was provided by the seller and the invoice was paid. The seller has indicated the item has been shipped and has requested that additional shipping fees be paid as the actual cost for shipping was greater than the invoiced amount.
How should I deal with this transaction?