After receiving two tickets in New York city, I decided to try this
service.  They claim to provide you with a dismissal letter that can
get your fine dismissed.  If you submit it and your ticket is not
dismissed, you get a refund of the fee, which is half the price of the
fine.

The problem is that the computer-generated dismissal letters I received
were full of factual errors.  They were unusable.  But when I asked for
a refund, I was told that since I had received these letters, I was not
entitled to a refund.

A scam, in my opinion.  

Stay away.