Bits do not train a horse. You must train your horse. If you cannot stop, turn and walk on and back up in a beginning loose ring level 1 snaffle, then you need to start over on the ground. After this has been mastered move up to a level 2 D ring snaffle and then into a level 3, either snaffle of short shank leverage bit. And remember, One should not have to ride their horses face in order to get response from him. Leg cues and weight distribution should be your foremost communication aides. The bit should only be used for guidance and lite corrections. Later on, depending on your riding disciplines, one can then go to other, more complex bits. And Always with Lite hands. =)
I'd gone with a "trainer" (I use the word loosely as he's really an idiot disguised as a trainer) so he could break a young mft mare for sale. An older woman was coming to look at her in a couple days and the mare hadn't even learned to walk on a lead. She learned this and was put under saddle, then trail ridden in the course of one day. I was on the mare they'd just gotten in, that nobody had even thrown a leg over, so the trail ride was to give the just then broke horse time to be on a trail. One day of harsh training and they were selling her as a trail horse. I was happy to hear the buyer passed on her..