even if you did change PL, This interference is intentional and he will just change his radio to another working PL. You will need an address, a name, a car license plate number and or photos for the FCC. You or others must do the investigation and provide as much information to the FCC, The work must be complete for the FCC to even attempt. Even then it is unlikely they will do anything, If it was an illegal business interference you would have better luck with the FCC, since they can issue a fine in excess of $14k. If you have any idea where the interference is coming from, you can find them with a yagi antenna and some attenuators.