Van has water contamination so garage has.

Van has water contamination so garage has changed fuel and filter has had 4 new injectors and after a week was given van back after they took it for a test drive I had it for about an hour and it broke down at a local car wash called Rac and they got it re started then in morning started moved to load up and when I tried to re start no luck so called Rac who took it back to garage they looked at it for a day and said no power to glow plugs so they took them out and phoned me to say they where all broken so engine needs head taking off it will cost me £750 now the first amount cost me £ 1120 so could anyone advise if I have been taken on a ride or if this seems a justified repair bill and am I liable for the glow plugs for they must have been working to start in the cold weather