How can you fight allegations and to clear a fine off your account from HOA

HOA sent a notice with a 1,400.00 fine.for illegal parking two to three cars on the roadway. For a period of 8 months we received the letter a few days ago. The cars are not ours. Rules are one car per house. They have sent notices and we responsed with the same answers. Not our responsibility to keep confronting people regarding parking when every homeowner was given a letter regarding parking. Every board member live on the complex they won't bother to call towing. There is a sign stating all unauthorized vehicles will be towed at the entrance. Our conscious is clear we did nothing wrong.