I would suggest going to the same source you bought them from. If they are legitamate, they should simply issue a refund.
If you purchased them through a "second party" you may still be eligable for a refund. Bad thing is second party ticket sales are often handled by criminals and they may be authentic. With home technology, this is quite simple. The scalper need only buy one ticket, from that, they match the paper, scan the ticket and simply change the seating number. Good luck, I wish I were more help!
