Santander is down in the UK, according to the website Downdectector.
There have been thousands of reports of problems with users in the UK unable to access their accounts.
Disgruntled customers have taken to social media to air their confusion and anger at the bank.
One Tweeter said: “Is Santander down at the minute? I can’t log on to online banking or use my card.”
Another said: “Same. It’s really annoying.”
“What is frustrating is they are always down on a Saturday,” a third annoyed customer wrote.
A Santander spokesperson said: “We’re aware that some customers have experienced difficulties this morning accessing our online and mobile banking services.
“These services are now working but there may be delays to making and receiving payments. We’re very sorry for any inconvenience and we are working hard to fix the problem as soon as possible.”
The bank’s website and mobile app banking services last went down on August 20th, locking hundreds of customers out of accounts.
Around 450 customers previously reported access issues to complaints tracker Downdetector.
Half of those who reported issues with online and a further 49% of people said they could not access their mobile banking.
One Twitter user previously said: “Business banking won’t let me log in. I’ve tried different devices and it won’t go any further than the initial log in page. Is the business website down?”
The bank went down on the same day last month as HSBC and TSB, leaving hundreds without banking services.
Speaking about the HSBC app, one Twitter user previously said: “I’m getting the same error message. But the HSBC website says mobile banking is not down.”
Back in May, Santander went down for the first time in the year.
Thousands of customers were locked out of the app and couldn’t access any online services.
Some customers even said that their payments were rejected in shops ad their cards “were not working”.
If you’re having difficulty logging into online banking, you can check websites such as Downdetector to let you know whether other people are experiencing problems with a particular company.