Airtel Pre - Paid Recharge — wrong information from airtel about recharge

Received SMS from SMS regarding talk time of Rs 88 after recharge of Rs.88. But when I recharged for Rs 88. git talktime of Rs, 77 only. SMS which is received from airtel is misleading or wrong SMS. Company is giving incorrect infromation as well as incomplete information to the consumers and net net they are cheating the customers.
Before this also, I got SMS from airtel stating the talk time of Rs. 50 after recharge of Rs 64 and will get the benifit new second rate i.e. 1 paisa per second.
After recharge I got Rs. 00.00 talk time. I have the same SMS for your reference, if needed.
I request to look into this matter as we are saving our paisa and company is taking unnecessary charges from us.