Adaptive Cruise Control problems of the 2016 Mazda MAZDA6

When driving, after a period of 10 - 20 minutes usually, of the adaptive cruise being on (not necessarily in use), the buttons on the steering wheel will re-map. That is, the + button for adjusting the cruise speed up by 1 mph increments will switch with the - button that adjusts the cruise speed down by 1 mph increments. This happens reliably. . . If I've driven the car with adaptive cruise on for more that 10 - 20 minutes, the buttons will re-map. + slows the car down or doesn't work at all (does nothing). - speeds the car up. Also, rarely, the cancel button will speed the car up. Often the cancel button will not work and the only way to disengage the adaptive cruise is to tap on the brake pedal. Less frequently--maybe about 1/3 - 1/2 of the time, the "off" button, which turns the adaptive cruise off entirely, will not work. Note, that this is not the "engage" or "enable" button. These are the buttons that just turn on and off the adaptive cruise and show that it is now ready to be set if on. I discussed this with the dealer. I believe it is a software problem, they cannot find a software problem as they patched the software in the car up to the latest version. They want to replace the steering wheel where the switches are. This is a $750 repair. (I'm not sure if it's the whole steering wheel or the switch cluster on the wheel. ) I cannot afford it and I'm not convinced it will work. I believe they are just guessing at a solution. Nothing to my knowledge has ever spilled on the steering wheel to potentially damage the switchgear. Also, this, to me, does not explain how it always works correctly for the first 10 - 20 minutes of driving, then fails reliably after that. This problem has existed for over two years. Since the car has had about 100,000 miles on it.