Ask HN: What to look for in an IT Company

What are some of the key components a small - medium sized corporation should be looking for in an IT company? (i.e. disaster recovery plan, remote back-ups, whatever)

I'm wondering what services are considered "essential", when looking for an IT company. We can pretend I'm building a checklist of must-haves, that the IT company in question would have to check all the boxes to be considered.

Or on the flipside, what are some red flags that your current IT company is... Not the best? (No word of a lie, IT Company X told someone at my workplace that their new computer's GTX 1050 has to be replaced by a lenovo on-board graphics to run multiple monitors...)

... "asking for a friend"