What rights do we have on changed seats

Angrybird

We bought concerts tickets in good faith, never having had a problem before, they were bought in Dec 12, then this week we received emails telling us our 3rd row seats had been changed to 11th row, they had rearranged the seating plan and taken seats out, some people had only moved a row, one of my friends has decided not to go, as she would not be able to see. We have emailed the promoters, who have not had the decency to reply, the ticket site deny responsibility, saying the promoters are responsible. How can they do this, with apparently total disregard for concert goers. It says in the small print that they can alter the allocated seats, but to put us on the 11th row, when we had 3rd is appalling. Can anyone tell me what if any rights do we have please.