There are fees, prorated charges, and other coats on your first and sometimes second bill that aren't reflective of the monthly price of your plan and any other costs, like finance or leasing charges for devices. Always look through your bill to identify these one-time or reoccurring fees that are in addition to the cost of your service.
If you are not happy with the resolutions offered to you. You can always file a complaint with the CRTC and CCTS to see if they can assist in getting you what you were promised or a suitable resolution.