Truth is if you're keeping your number all you need to do is tell the other carrier you want to port your number to them. Once they port over, your line will be cancelled. A short while after you'll get your last bill. This bill will include any negative tab balance plus any overages from the previous month. Koodo makes it easy that way.
Oh don't get me wrong, I still love koodo and will probably always try to promote it since I haven't had any problems with them, but my corporate plan at work tops any of the plans with data that koodo currently offers.
Still kicking myself for not getting data when koodo had it for a decent price.