Red, I'm not gonna read through this again but (and I know how this is easier to say than do) if possible next time it does this try keeping your foot on the gas, the other foot pressing lightly on the brake (enough to activate the lights) then press and hold the t/c switch for about 5 seconds to see if it'll disable the advancetrac. this may help in diagnosis if the tech is gifted.
Sorry AM this makes no sense to me. Besides fighting the car trying to keep it from going in the ditch or hitting someone else advanctrac can only be deactivated while at a complete stop with your foot on the brakes. I do know this during the first event the car would not respond to the TC button at all. Next Tuesday the blackbox or vdr gets installed.