Running any business is hard, booking people into exact time slots is impossible. For example in my job, if I were to book in a full weeks heating installation and you had an emergency gas leak, do I ask you to wait a week!! Give a busy man a job, he's busy because he's good!
I have a few trusted mechanics I can now use - two of whom are on here (Karl,Birdy)... But there are double the number that I would not take the bus to. One is a very large well known 'specialist' in a massive shiny tidy garage - but I would never give them any trade even if they were the last garage around. Use who you trust and who people you know trust ....