I already do a lot of work on the flat and over poles. It really only occurs when we are jumping, but thanks for your help.
Alright, so how functional is your "Flatwork" when you ride? Sounds to me that you are lacking in position to aid your horse to be functional when you are jumping.
If GP Jumpers can spend 5 - 6 days a week doing Dressage, and GP horses know minimally level 3 dressage, then why can't we incorporate this very important aspect of riding.
The question is - how do you ride? Our horses reflect 100% of what we do in the saddle, the instead of asking how you can fix your horse, stop and ask what it is that you could be doing incorrectly, to cause the result you are getting.