Cell C at it again!

The subscription of both of my Cell C contracts ends this year. One in July and another in August, my issue is that the one contract ended on the 24th July and they still billed me on the 31st August for the handset fee now i want to cancel and they say they can only cancel effective the 30/09 because they don't want us to lose the airtime. Please can someone call to explain what is going on.<br> <br> Thanks