Millions of Barclays customers are to be locked out of their online banking accounts over the next few months as the retail bank overhauls its network of digital services.
The banking giant has warned that both its telephone banking facility and smartphone app will be out of use for one weekend a month until January 2018 - 10 days in total until the start of the new year.
During the outage, customers won't be able to access their balance or transfer money over the phone or via the mobile app between 11.30pm on Saturday and 3.30pm on Sunday.
However cards will continue to work and customers will still be able to withdraw cash through ATM machines.
For all other banking needs, customers will be able to manage their savings and deposit cheques at their local Post Office - with 11,000 branches now open on Sundays.
The first blackout will be this Saturday - it will then occur once a month until January - except for December.
The bank is yet to disclose the full list of dates affected, however it has stated customers will be notified beforehand through its app, online banking website, or by text/email.
What's the black-out all about?
Barclays is overhauling its system to keep in line with new "ring fencing rules" that come into force in January 2019.
The bank – along with a number of high street lenders – has been ordered to separate itself into two legal entities - one for daily banking (designed for everyday customers), and another for more 'riskier' transactions.
This includes dividing current account, savings, mortgages and loans customers from areas such as investment banking, by the deadline.
The measures have been put in place by the Government as part of measures to avoid another financial crisis.
It is also issuing around 800,000 new sort codes to customers.
Across the board, a total of one million Barclays, HSBC and Santander customers will receive new codes as part of the switchover, which is scheduled to take place over the Easter 2018 weekend.
Customers will be written to ahead of the changes – you won't have to inform your employer or cancel any direct debits during the process.
A Barclays spokesperson said: "This weekend we will be carrying out work on our systems to align with new banking legislation to set up our ring-fenced bank, which will come into effect in the first half of 2018.
"We have worked hard to minimise disruption and apologise for the inconvenience this will cause to our customers."
The announcement comes just days after the high street bank confirmed plans to axe 54 branches by the end of the year to invest further in its 'digital 'and on-the-go services.
The move will bring its total number of closures in 2017 to 67 across the UK- although it says no job losses are on the cards.
"The number of physical Barclays branches will reduce overall but our branch network and the colleagues who work in them remain a vital part of our offering," a statement said.
"We will continue to evolve the shape and size of our branch network, as well as improving and investing in the experience in-branch. We also provide our customers with a range of digital channels."