Auto Lab Charged me WAY TOO much for services that could have been cheaper at Firestone! Troy, Michigan

Hello!I drive a 2000 Chevy Venture the van is old, but it's mine! I had an engine replaced in it about 6 yrs ago its runs fairly well and I  just want to be a little comfortable so of course I want the air conditioning to work as it used to! Didn't expect to come out of $250.00 for  a diagnostic????? Are you kidding me?? I went to Auto Lab Of Troy just to get my airconditioning checked out to find out what the problem was, also I had a right headlamp that was out, right turn signal, which I also over paid for my dad could have installed them for about $15.00 but he was unavaliable at the time, didn't want to get a ticket to add more problems! Anyway, I paid $99.00 for the evac and recharge, an additinal $85.00 for the diagnostic to determine if there are leaks???? I also  paid to have the connector wiring fixed is this included in the diagnostic?? When I drove off the premises I went about 20 miles and the air was warm again!!! Am I missing something here?? Took the van back this morning of course my condensor is leaking!!!!! Uhh what did the diagnostic cover???? Stan stated that oh It wasn't leaking at the time!!! But my argument is why put freon in a leaking condensor?? Wasn't the $85.00 diagnostic and the dye suppose to dectect a leak before I drove away??? Is it me or what? Then to add insult to injury Firestone has a coupon for $20.00 thats right $20.00 for a aircondtion performance check which INCLUDES the inspection of hoses and fittings and a compressor PERFORMANCE SYSTEM LEAK TEST run PERFORMANCE test!!!!!!! HMMMMMM that sounds like DIAGNOSTIC TO ME!!!! I am a cancer SURVIVOR!! I have battled and gone through a lot I just want to keep living as comfortable as I possibly can!! There should be a law against places like this I can understand being out of $85.00 for a diagnostic, maybe but 250.00 what did I pay for???? They could have said hey you need a condensor! We are not going to put freon in it!!! I'ts just gonna leak back out!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Signed Pissed off!!