Fired from sears? ? ? ? ? ?

I am 20 years old and live in salt lake city Utah, I was hired at sears as a cashier on 2/23/2011. I easily got the hang out things and did really well. My numbers were all good and I'd only been late one time. I was at 120% with my credit card applications (you are required to get 1 credit card app for ever $500 in sells) so meaning I was up a good number of applications. I had amazing customer service reviews. (we had a tv down stairs showing servey's that people filed out about how their experience was) and I was doing really really well and no negative reviews. So as I said my numbers for protection plans, credit apps, and customer reviews were good, I'd only been late once. But on Saturday 4/30/2011 I was called down to meet with my manager and he fired me because "I wasn't enthusiastic enough about customer service" as I left I spoke with the lead cashier and her supervisior about what'd happened and they couldn't believe it because they both said I was one of, if not the best cashier, they had. I wanted to know if there is a way to appeal this choice made by the store manager. My proformance speaks for itself. And I never received any warning about needing to work harder with customers or moved to another department (I've seen two people moved to other departments if they didn't work well with customers) I feel as if I was wrongfully fired since I was never even offered these options that others received. I need advice on this situation. Please dont lecture me, I'm asking for help, not someone telling me I did things wrong.