Trade problem

[DeGlekke]

A couple days ago I tried to sell one of my Mustang GT-R Concepts but I got a message saying there were technical difficulties with trade and I couldn't sell it. If I now go to sell cars or see it in my garage though it says that it is on sale on Xbox Live, but it doesn't show up by my sales were I can remove it, nor in the buy screen.
So does anyone have any suggestions how I can remove it from sale?