Gone are the days when TSB was Britain’s most recommended high street bank, named that in 2016, or when it was rated the best high street bank for service by Which?, a brand name used by the Consumers’ Association, dubbed so in February of last year. In the biggest IT migration disaster since the RBS shut out customers for over a week in 2012, the bank’s customers are facing an 11th day of disrupted or non-existent service either online or via mobile apps.

The complaints on Twitter include disappearing mortgages, access to other customers’ bank accounts, and payments to cable service providers for 81 years in the future. If it weren’t causing real misery, the spectacle would be amusing; claims by the bank’s Spanish parent Banco Sabadell of a successful migration of its 5.4 million customers, LinkedIn photographs of smiling, Cava-sipping IT engineers celebrating “victory,” and announcements by TSB’s CEO that problems were all solved last Tuesday have only done further damage to the bank’s reputation, branded “Totally Shambolic Bank,” by the Daily Mail newspaper.

The immediate problems began on Friday 20 April when the bank shut down its systems to move 1.3 billion customer records from former parent Lloyds Banking Group’s IT systems to the platform designed by its new parent Banco Sabadell. This should have been completed by 6 p.m. the following Sunday and, although celebrated as such, was nothing of the kind.

The problems, however, began much longer ago. Apparently, the Lloyds IT system was made up of a hodgepodge of systems inherited from the original TSB, prior to its acquisition by Lloyds, Lloyds Bank itself, and the Bank of Scotland, bought by Lloyds as a result of the 2008 financial meltdown, and other banks/building societies. This highlights a problem in the modern banking sector of too many mergers and acquisitions for the sake of volume and cost savings without any attempt to do the work of real integration at all levels. TSB had to be spun off from Lloyds in 2013 as a condition of taxpayer bailout money received from the European Union. It was then acquired by Spanish bank Sabadell in March 2015.

Although warned by many experts that its budget was insufficient for the IT change, Sabadell claimed that it was an expert in IT migrations and had done the same with dozens of small Spanish banks that it had acquired. Yet, the complexity of the task seems to have overcome its confidence. The move had been planned for several years—though delayed several times—because TSB was paying “rent” on the Lloyds system. It was an expensive arrangement and one that was getting costlier each year; according to the 2017 accounts, the annual rental cost rose last year from £91.8 million (U.S. $125 million) to £214 million (U.S. $ 291 million).

The original migration was set to occur in November last year, but CEO Paul Pester delayed the timing because it would have occurred at the same time as a possible rise in interest rates and the bank would have lost money if it could only quote for mortgages at the old rate even for a couple of days. And indeed, on 10 November, the bank increased mortgage rates. Pester estimated the cost of the delay to be around £70 million (U.S. $95 million) in additional rent. In a press release announcing the delay, Pester said it would happen in “Q1 2017.” With another rate rise possible in May, it looks like the bank, while not prepared, precipitated the migration to avoid that issue.

“We would never rush if we didn’t think we were ready,” said TSB. A demonstration of Proteo4UK, the system developed by Sabadell, was held in November. However, it does not appear to have exposed any problems. A spokesperson for TSB declined to respond to questions about the serial delays, but did confirm that the platform was subject to internal testing. "There was extensive testing that was completed before migration," she said. "There will of course be an investigation into why the migration did not go as expected." But the tests do not appear to have uncovered any problems. The bank was unable to confirm that Lloyds Banking Group had cooperated fully or been involved with the migration from its system.

In a written response to chair of the Treasury sub-committee Nicky Morgan, MP, Pester said that only a single transaction during the fiasco had been fraudulent and was being dealt with. The bank's spokesperson said: "Protecting our customers’ money is our number one priority and we work really hard to make sure they don’t become a victim of fraud.  We have a complex and multi-layered anti-fraud framework in place.  Our partners work with our customers too to make sure we stay one step ahead of the fraudsters." But Pester also said that the only customers able to see other customers’ account balances were those who shared control over accounts, such as a parent and a minor child. Even a brief review of the Twitter storm, however, shows that is likely not true.

The bank is currently being investigated by the Information Commissioner’s Office and the Financial Conduct Authority, and substantial fines are likely to result. In addition, compensation to customers is likely to run into the tens of millions of pounds. Any cost savings resulting from ceasing to pay rent to Lloyds are likely more than wiped out.