You normally need to complain to us in writing. You can do so using our online form, by post or in person.
There's an online complaint form on this website or you can print off a complaints form.
If you need advice or have difficulty with the forms or with access to our website, please tell us. Our contact us section will help you get in touch with our advice team and our accessibility section has information about what you can do if you have any special needs.