Consumer Redressal

I have been using a vodafone post paid number 9874474477 (Relationship no 1.26712687) for the last four and half years. Since November 2012, I have been charged Rs 35 per week on account of video downloads using a service called gossip_adda_videos. On checking this with the customer care, I was told that I have requested for this service. However, on my part, neither I remember of requesting the activation of this service, nor have I used this service even once. Now I am getting a blunt response from Vodafone that the amount that they have charged can not be reversed. I feel that this is one of the cheap trick from them to increase the bill amount, and would like to challenge the genuineness of their records.