I have a comparatively complicated water conditioning system comprised of a softener, carbon filter, injection pump and storage tanks for water, chlorine, and salt. As you may have guessed my water is sourced from a well with a pressure tank (air bladder).
I installed and maintain this equipment myself (except for the well pump). I find that its operation is simple and easy to troubleshoot.
There is no way I would pay someone to inspect any of this equipment especially something as rudimentary as a softener.
Your system may vary from mine and there could be a good reason why you might want to pay this person for this work, particularly if you are drinking this water.
I suppose your decision to hire this company would hinge on just how much you need conditioned water, or how much of a problem it would be if your system failed, concurrently, how big a health risk is it to drink the water if it is not properly conditioned or softened.
My first thoughts were that you’re being scammed, but without knowing the specifics I can't make that assessment.
Perhaps you should acquire a better understanding of exactly what your softener does and how it does it. You may want to contact this company and ask them for more information on what they do and how they do it. I'm sure this will preciptiate a few important questions and get you started on finding out about the water in your area and how best to treat it, how that treatment works, and what exactly you need.
I suspect they are trying to get you to pay them to tell you how they would like to upgrade your system. That industry is notorious for taking advantage of the novice homeowner or unsuspecting, ignorant consumer.