Contract expired but still a month's notice??

I decided to confirm with Vodacom what the process is since my monthly data contract ended on 27 January 2015. I wanted not to continue with my contract since it was not required for me going forward. Then the customer care consultant tells me that even if the contract expired this month, I should have called them to give 1 month notice. I thought this is unfair, why should I pay if I don't want to use the service, especially if Vodacom knows that my contract is expiring end of January 2015, why additional notice period from user.I was never told about this condition when I app**** for this contract 2 years ago and now I have to pay for an extra month for nothing. I have been a Vodacom customer for sometime and I didn't expect such a feedback. I will not recommend Vodacom data contract to anyone, there are many other service providers who are available for half the price with better network coverage where I stay. Terrible experience, also the consultant didn't even sound sympathetic, rather her attitude was more of demanding and didn't want to help for the questions I asked. I would have expected a firm like Vodacom to treat their customers with much more respect and understanding.