I agree with kaistiang that EVO should suspend that transction. However, this is not as per their TOS. So till the time "lemon" gets the funds back to his account, there will be some sort of anxiety.
I also believe that this facility should be a regular feature of EVO too just like paypal. I generelly like to make the payments through paypal, mainly because of this reason. Since it provides this facility, we can request them the suspend the transaction if we are scamed. Ofcourse, some time limit will apply for this facility which is quite logical.