Vodafone India — Activated service without consent

My vodafone number [protected]- international roaming was activated without any request from our side and simply a msg was sent which got ignored. When i travelled to china, my phone was charged 18000 rs which was a total shock to me. After repeated complaints for the charge incurred nobody helped us. I did not use the phone even once and since mobile data was on. It got charged by itself.
Vodafone employees have admited that they activated roaming and sent the mesg themselves but no body is ready to help on the same and forced us to pay the bill. Feeling highly cheated from the company whom we have been using from the past 15 years.