I tried to update the credit card expiry information, but it does not seem to keep. Tried it many times, with different browsers but it does not seem to keep. I even updated it and paid with the new expiry date info and it said that it will use it for next payment.
I still see the warning message on my account saying that the Credit card pre-authorized payment expiring soon.
It did not work. I then deleted my autopayment options. Waited a day, then went back in and created a new autopayment method with the same card but with the new expiry date. No issues entering it... it all went through. I then went to check the stored autopayment information and low and behold the old expiry date is there. So sad that a simple normal action cannot be performed by Fido. My guess is that it just will not take the same CC with a different expiry date.
You should be able to update you credit card without problem from your online account on Fido.ca.
Can you try to to clear the cache from your browser to see if you get the same result?