Is the Air Canada booking website down for anyone else?

Been struggling to book flights since yesterday afternoon. Keep getting this error message at the checkout page: "We're sorry, we were unable to confirm your account balance at this time. Please try again. If the issue persists, please try another form of payment. (BKRW-DBS-663)" Is this a card problem?

I know that on this website https://www.aircanada.com/ca/en/aco/home..html#/ there's an alert saying the website is undergoing maintenance, but the standard website https://www.aircanada.com/home/ca/en/aco/flights seems to be fine.

Anyone else having this problem / know the fix? Thanks!