Lenovo — invalid coupon code

Address:

Kanpur, Uttar Pradesh

i have bought a laptop from jumbo electronics at z square (lenovo g505) at 27th oct 2013.i have received a coupon code worth 2000 rs for redeemtion of diwali offer but it shows invalid when i try.i have already made a complaint against this essue but i have received same coupon code three time and it shows invalid.i am attaching screen schot of showing invalid coupon..