I cancelled my service in December and I did pay my December cycle (even over-paid as my cycle starts from 7th and I cancelled on 18th). Just now I received a bill of $45 telling me to pay for January. Please fix this because I have left Canada permanently.
When you cancel your account, you're only billed for services until the day you cancel.
If your cycle was the 7th, and you cancelled on the 18th, then your January 18th bill would refund you for the period of December 8 - January 18th.
Have you downloaded the bill to see what was charged exactly? Also, are you certain it's not a credit of $45 rather than an amount owing?