How to deal with traffic police fraud?

Traffic police on OMR randomly stopped and demanded 200 rupees claiming that i'm overspeeding when i was just doing 40 kph on the leftmost lane, calmly going to office. KTM irundha podhum pudipanunga. When i asked them they got aggressive and threatened to seize the bike. I had no choice so had to pay the bribe. Thiruttu kamnateenga, they are power drunk. Who to complain, what to do?