Where exactly does Visa acknowledge that? All I see is a blog post by Coinbase themselvs and that article, which used the Coinbase blog as a source most likely. lol
You can clearly see at the first blog by Coinbase that the text is a joint statement from Visa and Worldpay where it says: "This issue was not caused by Coinbase."
Maybe we could wait to see if they corroborate with the statement posted by Coinbase. But do you think they would lie? That wouldn't end well for them.
More:
http://fortune.com/2018/02/16/bitcoin-coinbase-overcharging-glitch/