Poor Service and Sim suspended

Location/place: Pune, Maharashtra

Name of company/service: Vodafone Mobile

I am from Pune and happily using my prepaid service of Vodafone. But one fine day I receive a call from Vodafone to convert prepaid to postpaid and suggested me plan of 249 rs and also took 250 as security deposit money. But then they activated plan of 149 rs and also after 4 days they made my sim suspended. I have cancelled my number immediately still they send me a bill of 500 rs where prepaid balance was not adjusted neither the security money they had taken as promised against the bill.I have all the proof of documents with me to file a case against them. Please atleast give my number back which I was using since last 6 years. my number is 9890599290