If you have a ticket and want to cancel it then you need to return it to United by the 6th May to get a refund, or alternatively you could give it to me at face value.
MU Travel are to announce how many additional flights they're putting on sometime later today. You're still looking at £800 min per person for a flight ticket though.
Best plan seems to be flying out to a European City a few days before the match and then fly onto Moscow either the night before or on the day of the game.