it will depend what van you have which no one has a clue what that is,if they are broken off due to seizure then a suitable drill and easy out and a good tap and die set could sort your problem out but careful drilling etc is required to avoid head damage,if access is difficult then the head may have to come off to sort out the problem
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix vans.