Homeowners have alleged that TSB Bank PLC breached their mortgage contracts by charging a 'disproportionately higher' interest rate, as a preliminary trial of a group claim worth up to £800 million ($1 billion) gets underway. The UK's Competition and Markets Authority (CMA) has found breaches of retail banking competition rules by four major high street banks, including TSB, HSBC, and Lloyds, under Part 2 of the Retail Banking Market Investigation Order 2017. These banks have agreed to take action to prevent a recurrence. Additionally, Barclays and TSB have issued messages to mortgage holders and have cut costs in response to the ongoing mortgage rate battle. In a separate development, 14 banks and building societies, including Barclays, NatWest, and Lloyds, are sharing customer data with the UK's National Crime Agency (NCA) in a crackdown on economic crime and 'dirty money'. This initiative is part of the largest project of its kind worldwide to tackle criminal gangs and money laundering.