By default, the Automatic Substitution is on for Repeat & Save, but you can disable this setting via the My Account section of the portal.

Your Repeat & Save subscription continues until it’s cancelled by you at any time or by Canon with a 30-day notice period.You can modify your Repeat & Save subscription settings anytime by logging into the My Account section of the portal. Enrolment in Repeat & Save is for your individual use, and not for resale, redistribution or to otherwise share with other parties.

In the rare instance that Canon removes a product from the Repeat & Save service (i.e. the product is discontinued) or cancels this service altogether, we will give you a 30-day notice informing you of this change. When signing up to other subscription services (such as Automatic Ink Replenishment), it is your responsibility to amend or cancel Repeat & Save, so you don’t end up getting the same products via the different subscription services.

Canon PG-540+CL-541 - At A Glance