Airtel — unauthorised deduction from my balance

My cell no is +91 [protected]
I am in botswana (Africa) wef 23rd november '17 on a personal visit
I have not asked nor authorised airtel to activate international roaming
I am shocked and surprised to receive a message yesterday the 29th that rs.99/- has been deducted towards international roaming rental from my balance
I do not want nor asked airtel for international roaming and i strongly object to your unilateral decision of collectingrent of rs.99/- without permission
Please revert and restore my balance and credit rs.99/- to my account without delay
Thanking you
R. Varadarajan
Camp: botswana