“Try again,” I said, knowing that there should be more than $6 in the associated checking account. But then it was rejected for a second time, and my mind suddenly was flooded with all recent deposits and withdrawals — trying to create a mental ledger of my personal finances. Was I broke? Had I been the subject of some sort of identity theft? And did I have enough spare cash in my pockets to buy my kid’s breakfast? (luckily, yes, I did).

Upon arriving back at home, I went online and checked my account balances. All good (read: I had more than $6 available). So I called the 1-800 customer service line, and was told that Santander’s entire debit card system was down. The representative didn’t have additional information, but did mention to me that she had run into troubles on the way to work, when she tried to use her own debit card at a gas station.

In other words, this was a big problem. Santander, headquartered in Spain, bills itself as “one of the largest retail banks in the United States by deposits.” It has 1.8 million U.S. customers served by 703 branches and over 2,000 ATMs, primarily on the East Coast.

But none of these people — including yours truly — had been informed of this problem by Santander. No emails, phone calls or text messages. I soon rang the bank’s Boston head of media relations, who said she had just gotten in and wasn’t yet aware of the issue. Two hours later, she sent me a statement that also was recently posted on Santander’s website:

“We are aware of an issue with our Santander Debit Cards. Customers can still use their debit cards for purchases by entering their PIN. We apologize for the inconvenience and are working to resolve the issue as soon as possible.”

When I followed up by asking if customers should have any concerns about personal information being compromised, or why the bank hasn’t reached out to customers, she didn’t have answers readily available. Nor was there an estimation of when service would be restored.

At this very moment, I would imagine that there are thousands of Santander customers being flummoxed by their inability to use their debit cards (particularly folks in restaurants or taxis who already have used the service that requires payment). So much for the convenience of debit cards, or the competence of banks…

UPDATE: At 12:04pm EST, Santander emailed to say it has resolved the problem. No reply still on security or customer alerts.

UPDATE 2: MasterCard provided the following statement Friday afternoon about Santander’s problems:

“MasterCard is aware of an issue that, for a period of time today, impacted U.S- based Santander debit transactions. This was the result of a system upgrade that took place at MasterCard and we apologize for any inconvenience this may have caused. The issue has been resolved, and all systems are operating normally.”