Do you have photoshop or paint shop pro, or other similar higher-end editor? If yes, there are a few ways to approach it that should work well - it might take a little time, and some closeup work - best to do stuff like this in small segments on the full-sized original photo. One solution would be to try a 'target' brush - this allows you to select a particular target like color, brightness, saturation, etc from one section of the photo, and apply them to another section. So you could use a sample brush to select the area without the reflection in each color range (the orange of the wall, the green of the window surround, etc), choose brightness and color on the target brush, and work it in with small brush strokes. Another solution would be to use a clone brush - it allows you to take wholesale sections of the photo from one area, and replace the bad part of the photo with it - you'd essentially be cloning the window below the reflection over the window WITH the reflection...again, with cloning or healing brushes, best to zoom in tight, and use small strokes.
Just a few ideas that might help. Post a large linked version, and some folks here might be able to do it for you if you don't have an editor that can.
