You call and describe what the door is doing - won't open, slams down, grinding noise, opener clicking but not moving. That tells us roughly what we're driving out with, whether it's a spring job, a track alignment, or an opener issue.
Once the tech is on-site in Surrey, Des Lacs, Sawyer, or Glenburn, the first step is finding the actual point of failure rather than assuming it's whatever broke on the last job. A cable off its drum looks a lot like a spring failure from the symptoms alone, and on an older torsion setup those two repairs aren't interchangeable. You get a price before anything gets replaced, not after.
If the fix needs a part we don't carry - which comes up more on original 1960s and 70s hardware than on anything newer - we'll tell you that during the visit, not after you've waited around for a repair that can't happen yet. For straightforward jobs, spring replacement, roller swaps, track adjustment, the work usually finishes in the same visit.