Infinity Insurance review: double billing

In August 2008 we took out a commercial vehicle policy on our truck. January 209 a motorist ran into one of our trucks. We were told that someone would come out and investigate. Instead all they did was pay the claim. So much for honesty and customer service, that was enough. According to there policy you are required to give a 30 day notice. We complied, only to be billed an additional installment without any advanced notice or anything in writing stating the purpose for the additional payment. We were also informed at the time of cancellation by one of their employees that there would be no additional billing.
Once we had received notice of the additional payment we contacted customer service to speak with a manager only to be refused and insulted by one of there employees.
We then sent them a certified letter May 26, 2009 only to receive a notice from a collection company dated June 8, 2009.
The notice indicates a cancellation date of April 14, 2009 when the policy was in fact cancelled March 9, 2009.
I have read the other complaints and I believe this is a kind of scam they run on there customers. Caveat emptor!