Passat pulling strongly to the left

Hi All
I have a 2004 VW Passat which is pulling very strongly to the left. As it is still under warranty I took it back to the dealer and firstly they told me they took it out for a drive and it was fine! I then took it to another dealer who said it was pulling but they could not find any mechanical fault and did a re-alignment. This has improved it slightly but it still pulls quite strongly to the left. Is there anything else I can do about this??
Jambo

Check tyre pressures.

Check your brakes aren't sticking.

If you've had an alignment it's too late to ask, but next time ask to see the spec before and after just to be sure they've done something.