Unexpected bill while on free tier

I received a billing from Amazon charging me about Adobe Media Server 5 Extended. I had an instance running on Amazon EC2 installed with Adobe Media Server 5 Extended image on a free tier. Since I had some troubles when configuring the server, I had to repeat the process of configuring another instance, and forget to terminate the previous one.

Then, I had 2 instances running Adobe Media Server, but only one instance was truly used (the one that was on free tier) and not the other. Due to this, I asked Amazon a refund, but they can only give if Adobe approve it.