Sangeetha Mobiles — goibibo promo code

Address:

Bangalore, Karnataka, 560047

I have made one oppo handset purchase from you forum mall branch in kormangala, and they have given me promo code for goibibo, unfortunetly till date i am unable to use the same, as it always says invalid.
They have also told me promo code is worth rs 5000 and can be used without any conditions.

Please suggest what to be done.
Purchase date - 20/6/2017

Awaiting your reply