Hi there,
When you check the previous month's PDF bill, do you see a notice of the increase? It should be in smaller print on one of the pages.
If you're not in a contract term, then koodo can raise the price of your plan using your PDF bill as their method of notice. I suggest you review the prev month, the steps to download the full bill can be found below. For some, this increase has been appearing as a plan change.
It may be worth seeing if cheaper plans are available in self serve that you can switch to as a solution to the increase, but they're allowed to increase it per the service terms.
https://www.koodomobile.com/en/help/viewing-and-downloading-your-bills?srsltid=AfmBOop9m-6B_OvZO9wPQZ8YNFrdNrD1DaDm5MdBldJb8MjlxRaWeXHT