Even if you consider the accumulator, maybe a few hnbr o-rings, and a diagnostic charge, that charge seems sky high to replace the ac compressor on that truck . . . even if the shop is using top of the line parts
Unless there was something lost in translation . . . I don’t know what, could be a lot of things . . . it sure sounds like this might be one of those bad apple shops that gives everybody else and the business in general a bad name