Being made to pay a month's subscription for a tv that's not being used despite calling to cancel

I don't know if multichoice creates new rules as they go but, historically we were able to switch off any unused decoders and switch them on again when they are being used. Yesterday we called because on the 7th of November we had called to deactivate a subscription which would be inactive for a month due to the fact that there's no 1 at the house. To our surprise we are told the cancelation would only take effect on the 7th of December.