For example, having one of your four printers not working isn't critical unless that is the only color printer in your office and you need a valuable price quote prepared in color this morning. Understand your support agreements in detail. Don't sign anything without knowing the commitment the vendor is making for support. Don't be consistently obnoxious or threatening to good vendors that provide reasonable explanations as to why response time is what it is. Successful vendors will have many customers and will at some point feel that the trouble is not worth it, and alternative vendors may be no better in reasonableness.
Humans make technology.
It also has many possible disrupters including electrical interference. While I have discussed this indirectly in previous columns, this is one of the most forgotten principles of technology. People make mistakes and those mistakes manifest themselves as bugs. Try to understand the nature and impact of the problem and alternatives to the timely correction of the problem before choosing your reaction. Things take time, especially with technology.