If you believe someone at work has discriminated against you, you should raise the issue with your employer. It's best to do this informally at first.
If that does not resolve the issue you can raise it formally. This is known as 'raising a grievance'.
You can also make a claim to an employment tribunal. It's best to try the other options first.
4. Getting help
You can get help and advice from:
If you're a member of a trade union, it might be able to help.
You can also get legal advice.