Install Crash Barriers on the M4 Betwen Junctions 11 (Reading) and 12 (Theale)

On the 30th of april 2010 my parents were involved in a horrific car crash on the m4 east bound carriageway between junctions 11 (reading) and 12 (theale) which my father was killed and mother was seriously injured my parents where driving a suzuki sx4 in the middle lane when it collided with a black bmw 335i, the speed that my parents where travelling at was about 70 mph my parents car left the carriageway and came to a stop at the side of the motorway and my father was pronounced dead at the scene, i have been to the crash site four times and along the side of the motorway between junctions 11 and 12 of the m4 you have crash barriers along side the motorway but how ever where my parents had come off the motorway there was no barriers installed i would like to no why and also how i go about changing or getting someone to install barriers all along side the motorway not just in some parts.had barriers been in place all along the side of the junctions 11 and 12 then my parents car would not have left the motorway and my father would still be alive and with us and my mother would not have been so badly injured .