Just log in to https://selfcare.time.com.my/ and you’ll be able to make any changes to the debit/credit card you’ve registered for Auto Debit.
If you have any outstanding amount, it will act to clear the outstanding amount (using that new card) and as well as to update/register the new card.
If you cancel your Auto Debit registration, you won’t be able to enjoy the monthly RM2 rebates anymore. You can make payment through any of the other available payment methods.