I have a 5yro mare, who is very heavy in your hands. She was badly broken 18 mths ago. She is quite difficult to turn and constantly leans on your hands. Height is no object when it comes to jumping but if she decides she dosen't want to jump she snatches the bit and darts out to either side. I have had her teeth and back checked every few months, everything clear there. Have tried various bits (Fulmer, D- ring, three ring, Snaffle) riding at present with snaffle and grackle. I need to get control before somebody takes a nasty tumble. Others ride her and I fear she may cause injury to others as she is quick and strong. Any advice???