Sending the bill even after the request fro cancellation of connection

Location/place: Delhi

Name of company/service: Telecom

I have a Vodafone post-paid connection of Bangalore. I have been using this number for 4 years, first with pre-paid and then migrated to Post-paid. I left Bangalore in April and I called them thrice in the first week of May to cancel my connection after the payment of Rs. 741 and I also send a mail to the Vodafone representative who had given me the post-paid connection. Come June and I get a new bill for the amount Rs. 446. I am frustrated with their customer support and I don’t want to pay money for someone else’s inefficiencies. Please help me get put of it!