It's a little different to my old automatic corsa, when I sit just say on a hill , I have my foot on the brake, when it's time to go it's off the brake and onto the throttle, if I think I'm going to be a while I just put into the park mode, and occasionally h/brake, so really you only need one pedal at a time, no roll back . But a couple of times today, I'm waiting at the give way, foot on brake, time to go foot off brake then throttle, instant rollback, I was sitting on a slight hill . I don't think you should have to use the handbrake at a give way unless you expect to be there a while. I know a lot if cars have a slight roll back but that is usually manuals, and people edge to up your bottom at times, so really can't afford even a slight roll back, il try and override the s/s see if that cures the prob.