If you have already gone into self serve and are having issues with adding the card remember that the website can be fussy. You can try different browser / clearing cache and sometimes private browsing / incognito mode. Confirm the billing address from your credit card statement is exact, including periods, spaces, capitalization and punctuation. If you live in unit/apt 206 and the billing address on your statement is "206-XXX street name" then enter it as that, and leave the apt field empty. Try removing / adding a space from the postal code.
Public mobile accepts Credit card or Visa Debit card issued by a Canadian or American financial institution and is registered to a Canadian or American address, or a Public Mobile payment voucher. The voucher can be had from recharge.com for payment, but not autopay, you can also register with autopay a pre-paid visa card for autopay, YMMV but I know that one works from Canada Post.
