Airtel Prepaid
Deduction of balance unnecessarily

I have recharged my mobile with rs.19 which provide me with free mobile internet for 3 days acc. to airtel but when i used internet services for the first time after recharge my balance deducted from my main balance which should not be done and when i called customer care helpline they are not bothered and not giving me satisfactory answer. please do sumthin my no. is 9929204029