Airtel — balance deductions for my account

Address:

Chennai, Tamil Nadu, 600049

Actually i have put a unlimited pack of 99 on jun 19 2018 (Unlimited calls + 100 sms free per day + 1 gb net for one month) for my mobile number [protected]. And my main account balance on jun 19 2018 is 35 rupees. But on jun 21 2018 amount of 15 is deducted for net usage actually i have data of 800mb in unlimited pack then how come you can deducted amount of 15 for net usage. Why you are cheating like this. I need a refund of my amount, i have all kind of proof to this.