Vivid Seats review: Tickets for wrong seatss

I bought 3 tickets for a concert in Charlotte 6 months in advance to guarantee I would get an aisle seat ( have a contraption on leg that doesn't allow it to bend very far). I received the tickets two days before the concert for different seats (an "upgrade" they're calling it) in the middle of a row closer to the stage. Nice, but not acceptable. The ticket price of the "upgrade" is $200 LESS than what I paid for originall and I cannot get a refund of almost $600. WHY? This is a scam.