water pump removal -- it's stuck!

[bmw318tiChic]

i just had a quick question about the removal of the water pump from my '96 318ti.

according to my bentley manual, it says that you remove the four bolts and then put two in the other holes and screw those in to push the water pump out. my dad and i have done that, and the metal top of the pump has started ripping apart, and the threads at the bottom of the pump feel as if they have been stripped from the pressure.

it seems like the pump is basically frozen to the engine block. what would you recommend that we do from here? is there any type of puller thing that we can use?

thanks so much