Airtel — special plan 399 rs validity fraud

Address:

Chennai, Tamil Nadu, 600119

Hi,
I have done recharge of 399 rs on my airtel number [protected] (Prepaid, chennai, tn) on 5 aug 2017 which give me unlimited local + std calls plus 1 gb 4g data for 84 days. By this mean, my plan should expire on 27 oct 2017.
But on 23 sep, i got message from airtel alerts saying that recharge your phone because your validity of special plan is going to expire in two days.
I am attaching the screenshot of my plan and message as well.
Kindly take action asap.
Thanks.
Lovish bansal