Close to 100,000 Lloyds Banking Group customers could be in line for compensation after the bank was found guilty of pressuring staff to sell products that customers didn't need or didn't want.
Regulator the Financial Conduct Authority (FCA) has ordered Lloyds to pay a £28m fine for its "sell or be demoted" incentive scheme.
The massive fine relates to incentive schemes used between 2010 and 2012, in which staff across the group's high street brands - Lloyds TSB, Bank of Scotland and Halifax - were put under huge pressure to hit targets, a tactic that the FCA believes "can create a culture of mis-selling".
It's the ninth biggest fine ever issued by the regulator and the largest ever for a breach of retail regulations.
The FCA investigation, which also revealed that Lloyds staff often persuaded customers to take out more protection than they needed, focused on Lloyds' sale of protection products and investment products, such as critical illness, income protection, life cover, personal investment plans and Individual Savings Accounts (ISAs).
According to the Daily Telegraph, it could also be that customers were urged to invest in funds when this wasn't suitable for them due to sales staff earning average commissions of up to £1,300 for lump-sum investments, £600 for protection policies and £60 for regular premium investment plans.
In Lloyds TSB, for example, advisers were typically paid between £18,000 and £73,000, based on six tiers. And failure to make enough sales would see them slide down the tiers.
The FCA's Tracey McDermott said: "Financial incentive schemes are an important indicator of what management values and a key influence on the culture of the organisation, so they must be designed with the consumer at heart.
"Customers have a right to expect better from our leading financial institutions and we expect firms to put customers first – but firms will never be able to do this if they incentivise their staff to do the opposite."
Taxpayer-backed Lloyds has already set aside more that £8bn to compensate victims of PPI (Payment Protection Insurance) mis-selling - by far the largest amount among UK banks.
At the moment, however, it is unclear exactly how many people are in line for compensation as a result of this latest scandal.
The FCA's investigation of a sample found compensation was due in 14% of cases, which would equate to around 97,000 people (based on a total of 692,000 customers who bought these products between January 2010 and March 2012).
But stock market rises mean many of those with investment products will have profited from the plans - meaning the bank will probably not have to compensate them.
Lloyds has promised to launch an internal investigation, prioritising 11,000 cases in which compensation is most likely. Those affected should be contacted as a result.
However, you can lodge a complaint by writing to the bank, or calling one of the numbers below.
If you are not satisfied with the response - or the bank fails to respond within eight weeks - you can also take your case to the Financial Ombudsman Service. Visit its website or call 0800 023 4567 for more details.
Customer complaints contact numbers:
Lloyds Banking Group – 0845 300 00 00
Halifax – 08457 20 30 40
Bank of Scotland – 08457 21 31 41
Lloyds TSB – 08459 75 87 58