The guy is charging you $100 to dispose of the compressor, but how much of that is being paid by American Home Shield (AHS)? I'm assuming the $75 that you paid him was AHS's trade service call fee (which would have been paid regardless), and that AHS will send you a bill for any portion of his fees that they don't pay.
I'm asking so as to determine what amount of money you're actually out, as opposed to what the guy charged.
If the amount of money that you're ultimately out isn't going to change the fact that you want to challenge this, then here's my suggestion. If I'm not mistaken, an A/C repair company would have to register with the Alabama General Contractors Board. File a complaint with them and allege fraud (
http://genconbd.alabama.gov/default.aspx). Alternatively (or in addition to the complaint with the contractors board), you may want to file a complaint with the Attorney General's Consumer Protection office (
http://www.ago.state.al.us/Page-Consumer-Protection).
Your complaint should suggest fraud due to the company's representation of there being a necessity for a disposal policy and disposal fee, when in actuality such a necessity does not exist. The only contents of a compressor that would require special disposal is freon. However, it's my understanding that you can not remove or change a compressor without also removing most of the freon inside, and that the EPA has indicated that any remnants of freon in the compressor is minimal and doesn't require special care for disposal.
It's also my understanding that these A/C companies use tanks to collect freon when replacing compressors, and that the disposal of those tanks costs them about $5.