Return payment fee on a credit card?

I am setup for AutoPay - the only service I subscribe to is Internet service which is why I am posting in this form.  My credit card number changed due to the Home Depot data breach.  

I received an email on the due date from Cox saying the payment was rejected; I immediately logged in and updated my credit card to a different credit card and made a separate manual payment on the due date so I would not be late.   However,  I was charged a Return Payment Fee of $25!

A Return Payment Fee is for a bank draft; why would I get charged such a fee on a Credit Card?  The payment was simply declined.  If your credit card is declined at a restaurant or store, you don't get a $25 return fee like you would if you bounced a check.  This fee doesn't make sense.

Further, I was told that if I had this issue occur again in the future with my CC number changing, I would likely still incur a fee because of how the payments are processed.  The CC payment is scheduled in advance - a 'pending payment'.  If you log into the website and change your CC info, it only applies to future payments - not the existing pending payment.  In order to update the CC info on your pending payment, you need to call in and have them explicitly update the CC info on the pending payment.   Otherwise the change only applies to the next billing cycle.

My question is this - why is the AutoPay system so bad? Why is it not more user friendly?  Its beneficial to Cox, you don't have to process checks that are mailed in, and you don't have to send me a paper bill.  Why are you going out of your way to make people want to drop out of the AutoPay system?

My CC number has been changed twice this year - Once for the Target breach, and once for the Home Depot breach.. The representative on the phone didn't know of  a way to prevent another fee for when this occurs again.  Can't we have a backup payment method or something?