Banks are often a law unto themselves. However, customers - both personal and commercial - can seek redress via the Financial Ombudsman Service.
Whilst the the FOS can help almost all personal customers of banks when it comes to maladminstration of their accounts, it can only help businesses with a turnover of less than £1 million. Nevertheless, it's not to be sniffed at.
A free non-binding service to users, the FOS, if it finds in favour of the complainant, can order the bank involved to compensate the customer upto £100,000. However, users - following the High Court case of Andrews v SBJ Benefit Consultants Limited - need to be careful as the judge found that a ruling, in favour of the complainant, had become binding.
What did this mean? Ultimately, the complainant who was seeking more than £100,000 couldn't use the courts as he'd effectively had his case dealt with by the FOS.
The moral of the story is to make sure of which path you want to take when seeking redress against the banks. It seems that users cannot take a twin track approach with the FOS and the banks - it's one or the other.