Escrow-Am I wrong ,how to trade.

[embrance]

So I agreed on giving 2.300USD on good.(0.16btc a the time)
Hired an escrow.
Then get a message saying shipping is higher,so they need 550USD more to complete the order.
As 2 days passed,btc went up,so my 0.16btc is now 2.670USD.So I ask the seller,to send over the remaining to complete the 550USD of shipping,170USD more.
But he says,no,its completely different.

In the mean time the escrow still has my money and I dont know if I or the seller is wrong.


Thought?

[Tactical Genius]

Well,trades are made at a specific time and so you should have agreed on a possible change in terms of prices of bitcoin changed.Come to think of it,if the prices had gone lower will you have been willing to top up?So these should have been settled before going on with the transaction especially in the face of bitcoin price volatility