I have had the same issue and it is so frustrating. There is a point where there could be a burner leaking gas since we don't know if it is completely off or not because we have no fricken knobs. This is a huge concern! Where can you get the buttons from? Sorry we lost the manual and I am desperate at this point.
Try Ebay. There are knobs on there for $16.00 up to $36.00 and higher. I have 5 broken knobs on mine too, but won't buy from Samsung ever again. Too bad, I really like the stove otherwise, love the convection oven!
Come on Samsung just admit you screwed up.