Toyota Service Failure

A little background, The vents for the center-left and floor closed and the controls to change vents became disabled. I brought the vehicle to the dealer under warranty. They reset the ECU for the HVAC vent controls and everything was fixed. The mileage warranty expiration was 3K miles away. I insisted that the problem be noted in the service paperwork because of being close to the warranty's expiring mileage. So, one month later, the same problem. Service checks codes and (six days later) nothing. Service now calls Toyota and Toyota tells them to reset the same ECU, they reset the first time. After resetting, everything checks out OK. Toyota now says since they can not find any problem I need to wait until it happens again. I asked the dealer what exactly will be done when it happens again and what is the difference between it happening again and when I brought it in the second time. When it failed the second time service checked it and had no idea what caused it. So when it happens again I will be right where I'm at right now. So here's where I am going, I have to experience THREE failures and be inconvenienced for days and the fix is NOWHERE in sight! Total failure!