I received a seat belt ticket even though I was wearing it. What should I do?

Hello, I got pulled over today by a FHP Trooper. The officer pulled me over to my surprise and said to me "I pulled you over today for not wearing your seat belt harness". I reacted in astonishment as if he was talking about my friend I just picked up from the airport. But he ured us that he was talking to me and asked me for my license and registration. I immediately plead my case and told him I did indeed have it on. He walked back to his car and came back 5 minutes later, ticket in hand. He went on to say "now Im giving you this ticket for wearing your seat belt improperly, sign here yada yada yada...". I was dumbfounded, irritated and completely confused as he wouldnt give me a chance to say much and cut me off every chance he got. I couldnt believe I had just gotten a ticket for something I didnt do. As I drove off, I looked at my friend and he was blown away as well. I thought for a second and said to him "wait a second, he said 'you werent wearing your harness' at first and now hes telling me that I was wearing it, but improperly?". Im not a liar, I have paid any and every ticket rightfully so that I have ever gotten. Never received a seat belt violation ever and pissed off to say the least that I now have a $119.00 debt that I shouldnt have! Should I fight it and plead my case? If so, should I bring my friend as a witness? I know there is no way of convincing someone on the internet that you were wearing your seat belt and wearing properly but Im telling the truth.