having been in the plumbing and HVAC since 77.....I would say your billing and breakdowns are over complicated.
It reads more like a health insurance bill than a service invoice.

I regularly service a few apartment buildings. Each unit (apartment number) is listed as to what is done, time and material.
trip charge is divided over all the units visited on a trip, that is added in the line.
I do not break down the price on every screw, bolt, bowl wax and supply tube.

Thankful I am close to pulling the plug....... looking forward to the day my phone doesn't ring.