I found the same this morning on my 1.5 deisel; I was lucky and was able to get some long nose pliers on to the broken bit and pull it out that way, be very careful not to push it in further!
You can remove the dipstick tube, there is a fixing at the top (13mm nut) and I felt one at the bottom which felt like a very small fixing - to get access you would need to take the engine under guard off and be very careful with the fixing as it will be rusty and you don't want more problems.
Phil, January 2009
