This weird thing happened to me, and I didn't know of a better place to ask about explanation. I recently moved my phone number from one provider (Fido) to another provider (Rogers). This typically only means I am closing my Fido account and giving permission to Rogers to take over the phone number for me.

Just now I received my last bill from Fido. I tried calling them to pay for my remaining balance, and they helped me with getting my CC info and paying out the last balance. I received a confirmation that the payment went through and I don't owe anything to Fido anymore. Good

But suddenly I received an email from Rogers that my payment method has been updated, and the new payment method was my own CC (I used a different payment method on the new account with Rogers when I signed up). How could that be possible? How did the Fido customer service update the billing information in Rogers systems??