User blog comment:Ghillie DReaMZz/Help?!/@comment-2207030-20120123225920

you have three options here. 1: You can try to play online with someone that completing the mission. 2: You can try to use WillowTree save file editor to reset the mission there by letting you complete it normally. 3: play a character on a second profile up to the point you are stuck and  then play splitscreen to finish the mission.

Hope that helps.