You can chose between an informal resolution, which means a chat with the police about the incident, or a formal resolution, which has the potential to lead to disciplinary action or in extreme cases charges being brought forward against the police officer(s).
In our experience, the outcome of your complaint will often be one you don’t agree with. An alternative process is to contact your local MP who may take up the matter. Otherwise you may also want to consider more creative ways to organise against police brutality.
We recommend that as well as making a complaint against the police that you also sue them for compensation through the courts. Although the complaint system and a civil claim are separate processes, they both have the same aim: holding the police to account.