Sorry, I can't help you with seat heat button.
My first 08 451 smart cabrio had heated leather seats. Absolutely HATE leather seats in a convertible. My 09 smart cabrio has heated cloth seats. I never knew any auto manufacturer offered heated cloth seats. I always thought default for heated seats were all leather. Because I drive my smart 99% of the time top down, I love cloth seats.
My first 08 451 smart cabrio had heated leather seats. Absolutely HATE leather seats in a convertible. My 09 smart cabrio has heated cloth seats. I never knew any auto manufacturer offered heated cloth seats. I always thought default for heated seats were all leather. Because I drive my smart 99% of the time top down, I love cloth seats.