I have a hunter/jumper large pony in training who simply will not relax and slow down. At the walk, she is constantly trying to trot, even at the end of a long workout. When trotting, she picks up speed every chance she gets and will occasionally try and pick up the canter on her own (I have the picking up the canter problem almost under control now). At the canter she is the most relaxed, although is still just a bit too fast for my liking.
I can keep her at the pace I want but only with constant playing in her mouth with the bit (snaffle). Half halts and see-sawing work great, but only temporarily. As soon as I stop she immediately begins to pick up speed.
I know working transitions is probably our best bet right now, but is there anything else at all that I can do? It is beyond frustrating having a large pony that won't walk!