donbrew

Attaching the overflow tank is very taxing job involving one bolt and one bayonet fitting and one push on hose. (sarcasm)

If they charge you labor for that; you have been robbed. For reasons I don't understand Mitchell gives a flat rate of 1.2 hours.

It is possible that the tank is broken a needs to be replaced, that is a different thing.

Silverfox

Here is a possible way to get some of these issues double checked.

My last 2 GM dealers offered a 26point Multipoint inspection FREE with an Oil change and AC Oil Filter. Approx. $40-$45
You are not obligated to have them do any work but it might resolve some of these issues and even some that the other mechanic missed.
As long as they do not actually do any work you should also be able to ask some
questions about what they find.
They document the inspection report and you can have a copy for you records and as a reference/comparison.
Give them a call and ask ... Pretty simple.

Just a thought.....

Silverfox