If a seller hasn't specified the shipping, how are you supposed to add it to the Ping payment once they do?

Sooo, I've just bought something where the seller did not specify shipping. Once the amount was specified, I couldn't alter the amount to be paid by Ping. I paid the seller directly to their bank account. Now I still have an outstanding payment showing, as well as a new 'service fee' owing. This seems like a glaring oversight by the brains who devised this new system. Are we now supposed to make two different transactions every time shipping isn't added to a listing? I love how this is marketed as 'No more success fees'. All they've done is effectively passed that on to the buyer, then char...