Cancelling my Vodafone Filmbox subscription was a nightmare

I joined Filmbox for free for one month through Vodafone's "gift wheel" promotion, but I want to cancel before the month is up. I have tried many times to get in touch with customer service, but I haven't been able to cancel. It feels like Vodafone is passing me around like a ping-pong ball, with no clear answer in sight. I'm upset and frustrated that Vodafone makes it so hard for me to cancel this membership. I don't even use the service, so I don't want to keep paying for it. Also, I don't want Vodafone to take any money out of my credit card without my permission. I want my money back in full as soon as possible. If you don't, I will sue you.