I perused your post and got from it that only $150 pertained to the idle problem, the rest assumably toward the a/c problem.
If this is the case, it seems that the shop only needs to make good on the idle adjuster problem. From your description of the shop, it sounds as if something has changed at the shop over the years leading to this less than satisfactory experience.
Anyway, if my assessment of the bill itemization is correct, it seems that they only owe you satisfaction on the throttle linkage problem. Although it is frustrating that they did not recognize the other problems, it would not seem that they owe you anything for that.
Is my assumption of the a/c problem being $,1050 correct? If so did they itemize what they did?