Appliance Expert 24-7

First, this company was very responsive and fixed my dryer within 24 hours.
However, I am very concerned re: the legitimacy/​ethics of their practices, which has been further confirmed when trying to find their Unilocal page. The numbers listed on the receipt operate under several different names, which certainly raises red flags re: legitimacy.
My situation: I needed to have the door switch replaced on my dryer. The technician confirmed that a door switch costs around $ 20. The final bill for service (including only 20 minutes of labor) was $ 324.77. I asked for a breakdown of the price, but the technician replied that he could not tell me that: «the office» set the price. I called the office and asked for a price breakdown (was I really being charged $ 300 for 20 minutes of labor?!) and the office said that the technician sets the price. I am very concerned about this practice: I believe that they are, essentially, making up prices. They assert they use flat rates based on the job, but were unable to tell me what the flat rate was for a replaced door switch– because «the technician decides.» Again: many concerns around the ethics of how this business is run.