Ask Slashdot: How Can You Find a Good IT Consultant?

Slashdot reader Thelasko says his wife manages a small eight-person business -- but remains unhappy with the company's IT consultant:
She's had endless problems with Windows 10 Pro's update system causing downtime. Anytime she calls the IT consultant, they don't resolve issues to her satisfaction, and the company gets stuck with a large bill. She's resorted to researching and providing support for the company network herself.
The contract is up at the end of the year, and she wants to find a new consultant. The company owner however, doesn't want to switch because all of the work the consultant provided is covered under a 'warranty' for 3 years (the company typically gets charged). I don't work in IT myself, and am unable to provide advice. What should they do? How would Slashdot find a reputable consultant?
Leave your best answers in the comments. How can you find a good IT consultant?

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