Along these same lines , I recently changed my routing , stops and carriers with an AA ticketed DONE5. There are lots of posts on surcharges , taxes etc. and if they are done correctly. I had all the data from my orignal ticket. The new carriers had lower surcharges and the stops less local fees. I calculated all would be @ $ 117 less than original ticket. AA came back as I owed them $ 6 when the $125 fee was imposed. IMHO AA is the place to ticket if you can.