I had the same issue several months ago. I hope yours is not the same issue but it sound just like mine.
I ended up having to have the airbag control module replaced and they are not cheap. After shopping quite a bit I found one for $1,300 which was absurd but better than the $1,800 the dealer wanted for it.
I found a couple of used ones but no guarantee that they worked. That fixed that problem at 62,000 miles.
I had a rash of electrical problems over a six month period and finally dumped the car. Hope you have better luck.