Overnight, the bank tweeted that it had taken digital banking services offline for four hours of fix work - and suggested access had returned by 4am.
The bank's online services have been down for nearly a week, after TSB's planned migration off former parent Lloyds' tech infrastructure - some five years after its split from the group - was a resounding failure. But in the following days customers were locked out of accounts, and some reported having access to other users' details.
The problems occurred as TSB was moving customer accounts from the systems of Lloyds Bank, which had been hosting the accounts for TSB, to the new core banking system Proteo4UK, a United Kingdom version of the system developed in-house by Spanish banking group Sabadell, which owns TSB.
TSB's mobile and internet app is still not working properly following major glitches related to a weekend customer account migration, meaning that although systems in the background are working, customers can not always see what services are available. That team of global experts will start working in Bristol, they will start working in London, they will start working across the UK.
TSB chief executive Paul Pester, normally so active on Twitter, maintained radio silence on social media on Monday as angry customers poured out their complaints.
The team will report directly to TSB's embattled boss, Paul Pester.
Shujun Li, a cybersecurity research at the University of Kent, said the main issue was not the initial failure - modern IT systems are too complicated and dynamic to be totally bug-free, he said - but because of the bank's poor risk management.
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For customers of Ulster Bank, which is part of Royal Bank of Scotland, the glitch will bring back memories of one of the banking industry's biggest-ever IT failures.
Many customers - who didn't necessarily choose to bank with TSB but were transferred to it from Lloyds when it was de-merged - have vowed to ditch the bank.
RBS paid a heavy price for its IT meltdown: fines of £56 million from the regulators and a £70 million bill for compensation.
The TSB board will also pay a price. After this week's debacle, it would be extraordinary if they were to receive anything extra at all.
It could also have long-term implications for the bank.
The news came with a trading update for the bank and its owner Banco Sabadell. "It is not overly generous as a budget for that scale of migration". But then, perhaps he couldn't get through on the phone either.