billing for unsent messages

Location/place: bangalore

Name of company/service: Reliance mobile connections

I have mobile connection from reliance since from 5 years, my billing amount always has crossed Rs500/- every time, I planned to further reduce it but to my surprise I came to know that people who are connected to me are getting messages (same message) more than 3 to 5 times which is increasing my bill amount. I complained about this to billing centre many a times but it is not rectified.
And I cancelled my caller tune but it is reloaded again next day with out my knowledge, making call to make correction is itself costing me a lot.