Vodafone India — billing issues

I requested for change from postpaid to prepaid but it is not done even after 3 months of application and the vodafone is still adding my bills on postpaid even after suspended services.
At the time of application i had cleared all pending bills even though they did not transfer my services to prepaid.
On contacting vodafone store they always dominate and order the customer to do this n that instead of solving issues they end up fighting with customers.