Speed Control Linkage problems of the 2016 Hyundai Tucson

Hi. I reported the cruise control malfunctioning to two different Hyundai dealers, service dept. The problem varies from not be able to set the speed, to not being able to lower the speed, to not responding to cancel, because cruise control will not work properly . All actions are by using the control toggles on the steering wheel console. It is an intermittent problem, as some times it works fine, and for other drives it won't engage at all, or will not disengage the speed when hitting cancel. I can tap the brake to slow speed, which can alarm a driver behind my lane and cause an accident behind me. The service staff can not get the cruise control to duplicate on a vehicle test drives. So with that, they say they can not replace the steering linkage, or any part because they can not prove it is faulty. I explained how it is not safe, especially on a highway with naturally higher speeds to consider. With five reports of the faulty cruise control on file, at different Hyundai service centers, the unsafe problem still exists in the tuscon 2016 SUV. I have paperwork showing reported safety concerns sept 18, 2018, Mar 27, 2019, June 3, 2019, August 15, 2019, oct 16, 2019. Plus a personal video of pushing and toggling the controls without cruise response. That is over a year of the reporting the malfunctioning speed control. It is unsafe with no solution.