You can tell us about the issue by registering / logging in to the 'my account' section of the website. 'My account' also allows you to view details of services you have previously applied, booked and paid for. You can also see updates on their progress.
If you prefer, you can tell us about a highway issue anonymously, but please be aware that you will miss out on the benefits of having an account ie. you will not receive progress updates.