Attempt to take advantage of senior destroyed property

MY elderly parents have a water softener and R.O. filtration system that needed checked as well as replenshment of salt for the softener. They were told twice to bring pellet and not rock salt. The tech checked the softener saying it was OK and then dumped 100kg of rock salt in the machine. It has ruined it, the sensors no longer work. The softener instructions clearly state NOT to use rock salt. These people charged my parents for delivery and now they want to charge a service call plus labour to come back and remove the salt they brought.
The same tech checked their R.O. and declared it not working and dangerous to their health, they should stop using it, discard the whole system and buy a new one. It's 6 years old and simply needs the filters and membrane changed. Obviously business is slow and they are preying on seniors. If the softener is not working to my satisfaction soon, Aquatrue will be the defendants in a lawsuit. We have already called the Better Business Bureau and warned them about this company taking advantage of seniors.