Quote Originally Posted by Lord Vukodlak View Post
the spell lasts minutes the control lasts until freed or the masters death.
Once the spell runs out the master is in command again.[who can also order him to resist any attempt to cast such a spell on him]
If the master vampire didn't think to give the order to not try breaking out of his control, that's his problem. Also, escaping his control for a few minutes is far from being of trivial use. For one thing, it could give the cleric the choice to not resist while his allies kill and resurrect him to get rid of the vampirism.