In such a situation honestly speaking, you don’t have any practical alternative. You need to record the incident if you have a device for it and present in front of the court if there is any suit lodged against you. You can also bring such an incident in front of the superior officers in the police department or can post the same to the social media site which can help you bring this incident in front of the public.
courtesy: DNA India
As per the law, the police officers have no right to thrash you. You can have legal options where you can file a complaint against the concerned police officer, but that will not make a huge difference in practice as the department is same and hence you need to raise the voice to superior authorities including the home minister and court of law. There are many incidents where the police officers misuse their powers offered by the system but to nab them there is no specific mechanism provided by the system, and that is why more of such incidents can be seen on the social media sites these days. If the department wants to take actions against such officers, it can be under the police manual only.