You might be able to adjust where the ankle strap is attached on the binding to stop some of that. Of course if you are experiencing heel lift in the boot then that could be part of the problem as well.
The knee pain could be caused by a wide stance, angle set-up, or also by the movements that you are making when boarding. Board stance set-up can take awhile to find that perfect width and angle combination for your individual body make-up.
If the store will give you credit and the cost of upgrading bindings is something that you have discretsionary funds for then I would recommend the Cartel bindings. I ride them myself and have been vary happy with them.
Last edited by gjsnowboarder; 01-24-2011 at 05:07 PM.
Reason: ie issues finished the post