The biggest problem for the auto industry is, No one likes paying. People go to the cheapest costing workshop. Which is totally understandable. If George at the corner workshop charges $90 for a service, Bob at the next workshop has to charge $80 for the same service, so he can draw in the customers. Its to the point where its pointless for workshops to be open. And unfortunately some workshop resort to shoddy work just to gain a buck.

My pet hate from when working in a workshop, is fellow workers treating customers like ####. Now I personally have a hate for arogant customers, but reguardless of whether I think a customers car is a ####box, should not reflect on the quality of workmanship. Its the customers car and maybe thats all they can afford.

Some customers treat mechanics like, " your just a dumb mechanic" and this leads to poor customer service and this is unfortunate. I believe its ok for a mechanic to perform unrequired work but your work carried out still needs to be quality and the customer has to be satisfied. None of this customer coming back and the mechanic saying "bad luck my car runs".
I have in the past and if I ever work in a workshop in the future, I probably will still perform unrequired work, but my work will still be quality. Like it or hate it. If your car doesnt charge the battery and its just a loose fan belt. I would consult you and quote you for an alternator overhaul. If you agree I would overhaul it like new and fit a new fan belt. I would even tell you your belt was on its way out and I replaced it for free. Your happy, I made a job out of nothing and still did the quality work I charged you for. Same goes for startermotors and starter relays.
Its wrong to charge for work you didnt do though. It might be wrong to overhaul an alternator when its not required. But alsong as the customer is happy - whats the problem. We all gotta make money. Feel free to report a workshop to The Dept of Fair Trading. But if you agreed to the work and received the work, you have no leg to stand on.

Customers need to learn respect - you go to the mechanic because you need them.
Then you will find more workshops will give quality work.
But reguardless, the next mechanic will still undercut your quote and this will continue to #### the industry