Vauxhall Corsa price for door repair

I believe that i have been over-quoted for a door repair to a vauxhall corsa, does anybody know roughly what it would cost to repair a door with a scrape down the side, around 1/2 metre long which is down to bodywork with a very shallow dent on it, approx 6 inches long. I have been told that the side impact bar is damaged and the door has been x-rayed??? Do garages x-ray car doors to check if side impact bars are damaged?? i have been quoted £500 for the repairs but have been told this is excessive. Can anyone help??