I have a 2010 EB.
For a couple of years now, mostly in the spring but occasionally in the fall, if you turn either front seat heater on, they both go to full and can't be turned off unless you turn the vehicle off. Sometimes they turn themselves on without pushing either button.
I suspect it is humidity related as it only seems to happen when it is cool and damp. Once it gets below freezing the problem generally goes away.
I am now noticing that the problem is getting worse in that it will come up more frequently.
To deal with it, I have typically unplugged the module under the front passenger seat that controls the seat heaters.
Now that it is getting worse and I've plugged it back in for the winter, it is getting annoying.
It seems sometime I can hit the button once and though both lights say on, the seats are not as hot so I think they've gone on low, but not off.
I generally like to fix things myself, but since this is an intermittent problem, I thought I'd seek advice from anyone else who's had this problem and has successfully had it fixed.