Do you mean that you have a new credit card that you want to use for automatic payment with Koodo and that you've updated this information through Self Serve?
If so, payment will be taken normally if you've done this early in your billing cycle. If your payment is due soon, the change may not take effect in time. When I do this close to a billing cycle, I have a habit of making a one-time payment. Worst-case scenario - I get double billed and then there's a credit on the account that's automatically used in the next billing cycle.
Please make sure that the name and billing address on the new card match the name and billing address of your Koodo account.