Did they do the tracking at the same time?
Go have a look at the tyres, they'll probably have arrows for the direction of rotation or "outside" if they're asymmetric - make sure they are on the right way around. Check the pressures
If they did the tracking at the same time then they've probably messed it up
Im getting lost. Was the car pulling to the left before the new tyres were fitted or has this started happening since you had the new tyres/tracking done?
My old Octy VRS pulled to one side under acceleration. After some research i concluded the suspension bushes were shot. I had the main control arm bushes and another set ( cant remember what they were called) replaced and the car tracked perfectly straight after that.
So maybe try the bushes, although if it isn't only under acceleration it might be something different.
or tie rods need adjusting. is the steering straight when driving on a straight road?