I paid for my item and then I get an email stating that postage cost more

[flatoutharry]

I paid for the item and then i get an email stating that postage would be another 4.75 I have not paid the extra as yet I have recieved the item how ever  I thought once postage was stated that was the price  How can a seller ask for more ?

[alexajames001]

I sell on another id and sometimes have underquoted on postage. Personally I would never ask for extra postage money from my buyer as it is my fault for underquoting.
I just suck it up.
As you have stated, you have received the item so it is entirely up to you if you want to pay them.

[lane-ends]

Maybe they are following Ebays example of quoting one post cost then charging another..

The correct way is you pay what was contracted in the transaction. If seller made a genuine mistake its up to you whether you want to help them out or not. a small private seller you might want to, a larger business seller I wouldn't bother, its part of the swings and roundabouts of business

[i-love-my-sheep]

I can count on 2 hands the amount of things I've bought where the seller underquoted on the postage. I sent one seller the difference. She was a first time seller and when I won the item I asked if she had quote the correct postage after she sent the invoice. I told her that if it wasn't right to adjust it in the invoice and resend it. I waited 2 days and didn't hear back so I went ahead and paid. 

When the item arrived, I noticed that she had underquoted me by a lot. As it turned out, she had actually gone into the red with that item by the time all the fees and postage came out. I felt bad that she had gone to a lot of trouble creating the listing, then packing it all up with lots of packaging, only to get absolutely nothing from the sale, so I sent her the postage difference. I figured it would only mean she's get a few bucks, but at least she got something.

The other sellers were high volume or experienced sellers who should know better. Those postage costs were even lower than if they got a postage discount from the PO. Another seller underquoted and I sent him a message asking if he wanted me to pay the difference and he said absolutely no, it was his own fault for under quoting.