MTS / Sistema Shyam TeleServices [SSTL] — Denied promotion offer promised by the company

Address:	688008
Website:	MTS

Hello, i had recharged my mts net card with rs. 699 on february 16th, 2016 as er an offer message received from mts.
-Message content-
50% FREE! Recharge ur MTS Mblaze no:[protected] with Rs.699 & Get 10.5GB (7GB + 3.5GB FREE) for 28 days. Offer only valid today

I called the customer service after recharging to register a complaint on not receiving the promotional balance. ( i was supposed to get 10.5 gb, instead got only 7gb).
They replied that i will receive the balance in 72hrs.
Till this day (march 5th 2016) i have not received the promo. Balance.
When i contacted the customer service, now they say that i had to recharge with rs. 201 to avail that offer.
This is cheating from the part of that company. If they provided an offer, they are supposed to give it. Not make unlogical explanations.
please take neccesary actions.