Declined Credit Card $25 Fee

I was just charged $25 by COX due to a declined credit card. I've never experienced this before from any company. I use this card regularly without issues, and have since used it without problems. I am unable to determine the reason it failed in this case. It is currently a valid credit card? Furthermore, there are various legitimate reasons for a credit card to be temporarily declined, especially given the prevalence of online cc security issues. As long as the issue is rectified and the bill is not overdue, there should not be a charge. This is not equitant to an overdraft on a bank check. This is ridiculous!