The ash situation brings back memories of the Dutch elm disease.
Getting back to Dans original post, I find it puzzling as to why a residential door company would not do the repair on his garage door. I worked in the trades for many years and found it a crap shoot whenever I had to rely on anyone else. Even in Canada that would be an astronomical cost for the repair. I have two 1/2" rods that I use to do any work on my garage door springs. I had three large garage doors installed on a new shop 10 years ago by a well-known company. It took them almost a year to get them working adequately during which time three different crews worked on them. One older chap finally recognized that one of them came with the wrong hinges. After all this one of the doors with a side operator frequently jammed. I stood back looking at it one day and could easily see that the left rail was on an angle inward at the top. I had to release tension on the spring and reposition the rail. I just cannot understand this incompetence. All they do all day is install the same item and still cannot do it right. I cannot count how many times that I was asked over the years to look at someone's furnace or A/C installation. Frequently found stupid mistakes made by the installers. Furnaces even come with very detailed installation instructions that apparently, they never read.