ACAS runs a scheme called early conciliation to try to resolve a dispute before it goes to an employment tribunal. This process is free, confidential and must be completed before you can make an employment tribunal claim.
This page from Citizens Advice explains the process in more detail.
There is also an ACAS leaflet: Early conciliation explained
If you are ready to start the process of early conciliation you can complete the form online.
If you do not have access to the internet you can start the early conciliation process by phone.
T: 0300 123 11 22
Calls charges (per minute)
Landlines: up to 10p
Mobiles: 3p – 40p (free if you have inclusive minutes)