I had a similar experience a while ago with Bank of America. Tried to pay my cell phone bill late one night - card declined. Called BofA, who said they couldn't access any customer accounts because of "maintenance."

I can't remember wether or not I used my BofA debit card (this maintenance was only affecting credit cards) or if I waited it out. BofA seems to enjoy conducting maintenance which makes it impossible to see your credit card account, but this was the first time that I couldn't use the card because of it.