Why wont my diesel corsa start?

My 04 corsa diesel wont start, It was having trouble starting but always eventually did, but now it wont at all, It keeps on trying but just doesnt kick in.

It will bump start and runs fine,

When starting there are no warning lights on but after about 4 miles of driving the service light comes on the dashboard

I took it to a vauxhall garage and they have told me that the egr(£60) is stuck open and that the high pressure pump(£580) is malfunctioning and both need replaceing,

I'm thinking that they are right about the egr but if the high pressure pump is malfunctioning shouldn't this be causing problems when driving? is a stuck egr enough to cause it to not be able to start?

any light shed would be really appreciated