Battery Cable problems of the 2005 BMW 530

My idrive showed a message indicating that the airbag in the passenger side was deactivated because of a sensor or similar issue. I took this to the dealer, asked for it to be covered under the previous service bulletin which indicated the seat mat sensor was defective. The dealership indicated they would not fix it. I contacted BMW north America and they said they might fix it if I paid for the assessment. The assessment suggested there was a defect in different sensor. And suggested that a battery cable should be replaced. All other systems in the car works fine. Both BMW and the dealer refused to fix this issue. There have been no other reported cases of the battery cable actually causing the airbags to be deactivated. Today, the airbag is still not working, and BMW has refused to fix the problem.