Hey Curtis,
Here is documentation on steps you need to do to reverse and invoice payment: http://www.tessituranetwork.com/Help_System_v125/Tessitura_v125_Left.htm#CSHID=View_Invoices|StartTopic=Content%2FTicket_Order_Processing%2FViewing%20and%20Paying%20Invoices.htm|SkinName=TN Skin
Hopefully that helps. I've had to do this many times. :)
Christopher Cuhel, The 5th Avenue Theatre