Insurance Query - Please help

Hi,

I was recently in an accident which involved 4 vehicles, me being one of the vehicles.. I would like some advise on views of what i should expect from my insurance company but furthermore any thoughts on who people believe is ultimately responsible?

So i was parked stationary at a slip road when a van behind comes crashing into the back of me... I then go into the back of another car which was also stationary. All the result of of lorry going into the back of the van which went into me.

Is it safe to assume the lorry driver who initially went into the back of the van which went into me is responsible and their insurance should cover the claim?

A few days have passed now and my insurance company is still trying to get in touch with the third parties to get there version of events but still had no joy. When i quizzed them on why they couldn't contact the third party they replied we tried to contact there insurance company but we were put on hold for too long so we put the phone down? I then kicked up a fuss as it was very poor customer service.. Now they have arranged for my car to be collected by a garage to be checked over etc to see the extent of damage.

How long does it usually take for an insurance company to get in touch with the other parties involved?

Also does anybody have any advice on any actions i should take?

Your thoughts and advice would be much appreciated.

Best Regards