I worked for a company years ago where we did c4 for about 2-3 years but decided to dump them because of continuous issues from their equipment.  Once we did we were no longer able to support the 50 or so C4 jobs we had.

FFW a few years later where I was a PM for a large company and C4 came a knocking.  In our initial meeting I point blank asked the rep "if we decide to no longer use your company, can we still support our clients that have your equipment?".  After attempting to beat around the bush I finally got a "no" out of him.

That's all the owner had to hear and C4 lost tens of millions (possibly in the hundred of millions) of dollars because of their decision to cut off dealers.