Why won't Fizz take my credit card information when ordering my sim?

You must have hit a bug, you need to contact Fizz.
Open a help page https://fizz.ca/en/faq/im-unable-log-my-fizz-account-what...
wait for 15 seconds and you'll see a bubble chat at the bottom right.

I 've had a related bug as well with my CC... but after i logged out and tried again it took my cc...

Have you just tried to log out, clean your browser history, then try to reconnect? Sometimes it works. Maybe there's a problem with the cookies or something like that.

Is your card at your name ? Do you have the same address in your account and your bank/credit card.
If the answer is yes to all my questions I suggest you to contact Fizz on Messenger.

Some credit cards are sadly not accepted for no apparent reason

Try another credit card or contact fizz

"Why won't Fizz take my money?"

Hehe tell that to those where Fizz got their money but haven't delivered :P... but this is probably a glitch

Contact Fizz

Try to relog , try another Credit card , they had problem with the Mastercard at first.

Try other card. If it's same, it's a bug