Simply call Chatr Customer Care at *611 from your chatr wireless phone– a free call or call 1-800-485-9745, from anywhere in Canada, and a friendly chatr customer service rep will be happy to assist you with this.

You may need to top-up your chatr account to ensure there’s enough balance to cover your new plan’s monthly fee. A new anniversary date will be created for you as well, based on the date of the plan change. Changes will take effect immediately.

Source