unauthorised deduction from balance

Location/place: porbandar

Name of company/service: uninor

I am having the prepaid mobile no. 8732910820 of uninor. On 30.05.2012 and 06.06.2012 the company has deducted Rs.15/- each from my balance without any reasons. On complaining the customer care of the company, they neither give satisfactory reply not they have credited the unauthorised deducted amount. Please do needful.