Hp - Pavalllion Laptop — regarding false commitment

sir,
i bought a hp laptop on 5jan2009 from lucknow.ther is an offer to me that u purchase this laptop
and fulfil the other hp-company's formalities, then u will get 5.1 channel phillips home theater system of Rs 10990.00 with in 6 weeks as a gift.
i calls nd mails many times to hp, hp redemption cell but there is no gift recieved by me till today.
they always say that pls waite i will send with in 10 - 12 days.
in this condition what can i do against the company????
so pls short out this problem asap.
with warm regards
jaideep