I was very satisfied in the end.
Someone from Academy Overhead Door came to fix my broken spring. After he worked on it, the spring was opening and closing fine but making a funny noise. It rattled a bit when the door came down.
I knew their work is guaranteed, so I called them to make another appointment. It took me a long time to get someone back out to see if there was anything seriously wrong. Fortunately, it turned out he just had to apply some grease.
I think they were running a special on door repairs, so that's why they couldn't get back to me right away. The experience was still very good overall.