The banks control a large amount of the KiwiSaver market with the two largest providers - ANZ and ASB having a combined market share of around 47 per cent.
The Ombudsman has released a KiwiSaver guide providing information on who people can complaint to, the main types of cases it has seen, compensation and examples of certain scenarios.
People may be able to withdraw savings from their KiwiSaver account if they meet certain financial hardship requirements.
These include showing that alternative sources of funding have been explored, completing a statutory declaration on assets and liabilities and providing documented evidence to support the application.
Whether the application is approved is down to the trustee of the particular KiwiSaver scheme to which a person belongs.
If a person is not happy with how the trustee has handled their application they can complain the trustees' financial services complaints scheme.
The Banking Ombudsman is unlikely to be able to handle trustee related complaints as trustees do not belong to its scheme.
Read an Ombudsman guide to KiwiSaver complaints here.