I believe you said you had the tires balanced and the wheels aligned. Did you also have the tires rotated? Assuming the alignment was done correctly, this will be due to a bad tire. A tire can develop an internal chord separation that cannot necessarily be seen from the outside. This can cause what is called a tire pull. A tire with this problem cannot be repaired but must be replaced, however, sometimes if placed in a different position on the car, the pull will not be as noticeable. This will be one of your front tires. Try swapping the tires on one side (front to back and back to front) and see if it helps.
Thanks for your reply with valuble advice. All tyers are new June 2013. And I've rotate twice; onec, the front tyres lfet to the right and again the rear left to the front left as wel. somebody told me its a suspension!!and a computrised elignements as per TOYOYTA specs was done not manually?