Seller wants more money for postage

[wookiethecat]

I bought an item 8 days ago. Seller messaged today saying I hadn't paid enough for postage and had to pay more before she can send it. The postage is set by seller - if they undercharge that's on them right? I wouldn't even know how to send more money. 

[*guinevere*]

Tell them politely that you do not intend to send them any extra money, that you have paid the asking price and you now await the arrival of your item.

If it doesn't arrive you can open a not received case the day after the last estimated delivery date to get your money back and leave appropriate feedback.