validity Deduced from recharged plan

&lt;p&gt;&lt;b&gt;Location/place&lt;/b&gt;: pune&lt;/p&gt;<p><b>Name of company/service</b>: tata docomo</p>Transaction id : 100002493351786
Date & time : 18th March, 10.18 am
amount : 124 rupees
mobile no: 8446629148

My Tata docomo no. is 8446629148
I am recharging rs 124 on 18th March to this number for free Tata docomo to Tata docomo call for 28 days validity.
but when I am reacharged, the company gives me only 21 days validity. when m calling customer care that time they not gave me expected reply.
So plz give me 28 days validity otherwise ask to pay my balance.