The Spanish-owned bank Santander was this week fined £12.4m for giving customers poor investment advice.
The Financial Conduct Authority said Santander failed to guard against customers being given misleading information about its products.
It also said the bank did not monitor its investments under its Premium brand, which was flogged as a tailored service which reallocated cash to best meet the customer's needs.
The FCA's investigation also discovered shortcomings in the bank's training and monitoring of its advisers.
Interestingly, if it hadn't been given an early settlement discount of 30 per cent, Santander would have had to pay a fine of £17.7m.
Santander UK has promised to contact affected customers and offer redress where appropriate, but claimed the level of customer losses would be low.