The only 'charge' to change to koodo is settling your final bill with telus.
Also if you would like to port your number to koodo, keep your telus account active so you can port your number to koodo at a kiosk (this will automatically end your service with telus). There are no activation charges.
Also if you decide to bring over your telus phone (it may have to be unlocked) you get 10% off your monthly plan.
The only time you would get charged on top of your monthly plan is if you have a tab M or L in which case there would be a $5 or a $10 tab charge. If you have anymore questions, feel free to ask :)