Did you come to my shop ( Midas Bronson)? I did not remember you and I did not do any O2 sensor work for our Chinese friends recently.
Normally we don't charge the scan fee if the work done in our shop. 360 to replace one O2 sensor, not expensive? What kind of car are you driving?
Have no clue which Midas did you go. We don't fill the tire pressure to "29"psi. If we could not find the specific psi number from the car we refill to 32 or 33psi depend on different cars other than in winter. Yes in winter we recommend to refill to the pressure less than about 2 psi. It will be safer in that way.
It is up to you to watch mechanic fixing your car. All the mechanics in our shop have the workplace safety insurance. Anything happens to them (it is not good thing for sure) it will be covered by the provincial government. If you don't care yourself or if people have enough liability coverage they can stay in the shop, I have no problem.
By the way, no people can make money on Winter maintenance package. Normally people loss money on those kind of services.