Please help with summons issued in Rome?

I visited Italy last year in June 2010. Yesterday I received a notice requesting payment for a summons supposedly issued to our rental car for driving on a taxi lane. I asked them to send me pictures of the infraction and they sent me two separate pics - one of the back of the car and the other of the street where it supposedly happened. They did not send a picture of the car driving down the street. Has anyone ever experienced this? A year later they are claiming payment? If I am responsible, I will pay. But shouldn't they show me a picture of the car driving down that street? The fine is for 99.88 euros! They also told me on their response that if I appeal this issue and they deny the appeal, the fine will double. Should I just pay or appeal?