Vodafone Mobile Service — provided misleading information about new plan

i have a vodafone postpaid connection ([protected]) since 2005. it was gratifying to note that the service was good all these years. but last month, i received a call regarding plan change. a life time plan was suggested for Rs.500/- availing which the vodafone executive told me that my monthly charges will be down by 40%. but when i received my latest bill, i was in for a shock. not only was the monthly charge high but the bill amount exceeded the previous 3-4 months' bill. when contacted customer care, they coolly replied that the 500 rupees cannot be refunded. the executive was unable to provide proper information, casually gave an email id and asked us to register a complaint. this is not becoming of a reputed company like vodafone. they are answerable to the charges failing which i am planning to move to another service provider. they also had the audacity to call us last week and inform about another plan of add-on connection which when again inquired the executive told me that there was no scheme like that. what is this contradiction? i fail to understand. vodafone should refund that Rs.500/- and pay for the mental agony of the customer.