How can i slow down and collect my horse better??

[Brittney]

I have used this horse for about three years but just started showing him 2 years ago, and before i used him he wasn't very broke. and he is 7 now and i have got basics on him but still havent got him to have the greatest/consistant lower head-set and slower lope. I have done many stops and back ups but it seems like that is only helped so much. and is there a better bit to use for collection that isnt that harsh.