This is still a problem, and it's bigger than Rogers. I left Virgin in frustration because I could never set up a credit card on their website and it was always a big freaking process when a card expired to get the new one on there. Went to Rogers, and same thing - it didn't like my CapitalOne Costco Mastercard, or my mbna Visa. I went to Rogers in person and the guys couldn't add the cards either, even though I bought my new SIM card with one of them. I finally got it to work with a Tangerine Mastercard that I otherwise NEVER use, so now I have to keep that dumb card just because it's the only one that works with cellphone companies, apparently.
If it still doesn't work, you may wish to try the other contact us methods. Of course it's important to enter the syntax properly, not to make any typing mistakes or transposing expiry dates. Usually you enter the CC number without spaces, etc.