Airtel — wrong bill generated by airtel postpaid of month feb-19

Address:

H no 37 Gali` no-2,Awas Kunj,Phase-2, Laxman Vihar,Gurgaon, Gurgaon, Haryana, 122001

Hi,
I am facing issue due of airtel postpaid wrong bill generated of my airtel mobile number-[protected] (My child number -80xxxxxxx34). Airtel team activated international roaming pack at my mobile numbers (All three numbers) without my information and i did not get any information. When my number 80xxxxxxx34 go in international roaming, then automatically international roaming pack was activated and my bill reached approx 6100 rupees. Always my bill come average of 700/-, but now cheating of airtel team my bill was reached more than 6100 rupees,
So please help me to resolve my issue.