BTM,
I can see why you would be frustrated.
I also have varix III' s on my rifles.
In a perfect world when you adjust your scope 10 clicks up and 10 clicks down your point of impact will move back and forth to the same spot.
Unfortunately that is just not what always happens. Maybe for some people this works but it has never been my experience, expecially shooting at distances over 200 yards.

If you are adjusting your scope at the end of your shooting sessions and don' t check to see where your zero actually moved to and then when you go out to shoot again the zero did not move to where you expected it to then I am not surprised.

Even with a vari x III you have to actually check your zero and fine tune it to make sure the adjustments moved the zero to where you want it. Especially at 200 yards and further out.

Try leaving your adjustments where they are for awhile and see if you still get point of impact changes.
Good luck!