Closing account partway through month but getting charged for full month

So I rang Slingshot to cancel my account with a final date of 2 February 2013. My billing cycle is on the 18th of each month so the person on the phone told me I will have to pay for a full month of service even though I wish to cancel partway through the month. I'm not sure if this is normal, I've been told Telecom will bill you pro rata if you cancel partway through a month.Anyone have ideas on what I can do? I really don't see if being fair to pay from 2 February to 18 February when I won't even be living at the residence anymore.