Airtel — did not get the intended offer for which I paid.

Address:

500062

I have recharged my airtel 4g mobile with 399rs for which company was offering 70 gbs data for 70 days and unlimited calls local/ std. An sms from company also showed that the offer is activated. But when i checked last in my airtel app it showed 28 days validity instead of 70. I felt cheated. Airtel customer service does not respond to my calls.
My mobile device is 4g enabled and the sim also is 4g sim. So there is no way airtel should be changing the offer plan. Which was intended for 4g handset + 4gsim.