I may have this wrong but of your wrist is sore after a days casting then it sounds like you are using it excessively, there are a couple of things you can do, first is buy the Lee Wulff Wrist lock, that helps, in fact if you wear it for a couple of weeks you will be cured of excessive wrist break.
What I did was to use some string, tied around the rod butt and tied around my wrist, 20 minutes per day casting with this on, if I tried to use to much wrist I would certainly know about it, after 3 sessions my wrist control improved immensely, to the point that my arm wasn't marked after removing the strap. You could also make it out of strong elastic.
Remember though, slight and controlled wrist break can be a very good thing
A lesson may help, I think
Phil Ratcliffe is near you
Chris