Vodafone India, Kolkata Circle — get 28 days validity whereas should get 30 days validity

Address:

Kolkata, West Bengal

My vodafone number is [protected]. I search for 3G data plan by dialing *111*6# & have got more option & I choose option 4 & press send button & again I get more option & select option 2 on dated 08/05/2015 & get information that 3G 1GB data free for 30 days with recharge amount Rs251. I recharge with aforesaid amount on dated 08/05/2015 but get 3G 1GB data free valid for 28 days (i.e. upto 04th June 2015). I contact with vodafone customer care but they have replied me the validity period for 28 days is correct and 30 days validity which I see by dialing *111*6# is update problem. So please take necessery action against this matter.