Air Bag Not Deploy problems of the 2012 Infiniti EX35

Passenger airbag light came on. Brought to dealer who advised sensor needed to be replaced. Replaced at $593. 14 before tax on 3-22-18. On 4-27-18, light came back on and returned to dealer who advised entire bottom of passenger seat needed to be replaced. Additional cost before tax was $2,201. 21. Advised problem was that the airbag may not deploy in the event of a crash. Specifically, the airbag light came on each time the car was started. Have retained all records and invoices. Vehicle never in an accident and nothing happened to the passenger seat to cause a problem.