Mobikwik — Cheating by fake offers

Address:

411032

Mobikwik had started an offer of Rs.300 cashback on adding Rs.300 through lumia mobiles on specific models and regd with mobikwik before 15 Nov. LUMIA 535 and 430 were two of them. I purchased the above mentioned mobiles because of the cashback offer. In Dec they withdrew the offer and did not give me the cashback. In Jan and Feb they gave cashback with different code. Now in march, they are not giving the cashback and stating that they have withdrawn the offer as per their terms and conditions. But the offer was valid for a year.
This is complete cheating and unethical. They cannot issue an offer for selling a product and withdraw it at their wills and fancies. If that is the case, they should buyback the handsets also at original price.