Banks are involved in commercial and industrial transactions but also become involved in many different types of domestic issues such as wills, probate and investments. The same regulations over professional negligence are exactly the same whether the bank is dealing with another large corporate organisation or an individual.
Providing financial loss of the customer has insued and the customer can prove that the bank has a duty of care (not difficult to prove) then a compensation claim for professional negligence can be made against the bank.