Officer changed date on traffic ticket and never notified my son before submitting it...?

My son was issued a traffic violation for hitting a mailbox, the officer gave him the ticket with "call within 20 days" written in the court date section. He called the court 10 days later and was told he would be notified by the court as to his date, the officer should've known better than to write down this message. Having heard nothing from the court, I called myself after Christmas and found out the officer had changed his ticket copy to reflect a court date of 12/11/07 before turning it in. The secretary of state's office sent my son a letter saying his license is under probation because he did not contest his citation--presumed guilty plus a bench warrant was issued and fines essed for not showing up. We immediately went to the courthouse with the original ticket, which was photocopied and the warrant and fines removed (so they say). Can this be grounds for dismissal? What happens to his driving record since his court date is not until April 3? Why would he do this? Help!