An awkward, reclusive, unusual young man with a wealth of trust fund money strikes up a friend with a hapless anti-obesity crusader who comes knocking on his door for donations.
American Airlines has a whopping $200 change fee on paid fares (other than full fare refundable tickets) for domestic flights, and up to $450 for international flights. Same day changes are $75 in economy and free for business and first class passengers on paid fares.
The $180 cost to change your flight is that $150 change fee, plus the fare difference of $30. This is clearly noted in the fare rules that you agreed to when you bought the ticket, whether you are happy with it now or not.