To add to what JJJeffrey said about changing to a business class award routing - Assuming you are seeing "C" inventory when doing award&upgrade search for the individual transatlantic flight only (not part of a routing with multiple segments/connection), also search for "U" inventory. This would mean you can call and change the coach redemption to a business class redemption for the difference in miles. Considering a paid discount coach to business award is $350 + 25,000 points, going from a coach award to business award may work out to a better value anyway...