Seat belt and airbag did not work properly in an accident

The seat belt should have locked, so that is a question for someone who can actually look at it. As far as the air bag, if the clock spring was bad, the airbag light would have been on indicating a problem. If it was not on, you have to keep in mind, the vehicle needs to take a hard hit to deploy and in the right place.

A bad clock spring would prevent the bag from deploying. Even if the SRS light was not on, the ABS or Tracs light would be on.

Without actually scanning the vehicle it would be hard to give you advise. The dealership would need to do that since your vehicle has a black box. You may need to get a lawyer for those records.

How did you hit into the ditch? If you hit directly into the front of the vehicle and "stopped" they both should have deployed. If you sort of slid in sideways and did not hit real hard the sensors may not have tripped. As JIS says, you can hook a scan tool up to the SRS system and it will show the various forces and whether or not it should have gone off.

But you also mention having a possible bad clock-spring. If it was bad it should have activated the airbag light and disabled the system. That as well would show up in a scan. As JIS also says, you will want a lawyer involved because you may end up in court if it shows the forces involved should have activated the SRS system but did not.