Failure to stop and prvide details and due care and consideration?

I received a NIP for the above offences. I was stopped in town by a very angry driver who accused me of cutting him up at a roundabout and causing him to drive onto the roundabout and into signage. After he stopped me and wrote down my reg number he went to report me to the police. I couldn't provide insurance details as I didn't have them with me but did offer contact details.I wasn't aware of any incident, I was involved in no collisions and the chap stopped me 2 miles across town from the point of the alleged incident. Not sure whether it was mistaken identity or what. He swerved across the traffic from a bus lane and parked across 2 lanes to stop me. Pretty scary. What do I do?