Advice

Unfortunately I was reversed into and it has cracked the front bumper and chipped the grey surround, insurance company are sending out an engineer as I am reluctant for them the just to repair it using filler etc, my preference is a new bumper.

Do you have any say in how you want the car repaired?
 
Yes, insurance should return your car to the same standard as it was in pre accident. If there will be any noticeable difference then they will use new parts.