Be wary of National General Insurance

In any one vehicle accident you will need comprehensive and collision coverage in order for your insurance to pay. I know many insurance companies have repair shops they recommend. They often also guarantee repairs from these shops and tell you if you choose to use a facility not on their list their liability ends as soon as you sign off on the repair. If the door falls off as you drive away or they failed to do quality work, that's between you and the shop, the insurance company is now out of the loop. I really didn't see anything out of the ordinary in your claim experience. The wreck was on you, the location of the guardrail is not their concern and repairs always take longer than we want. And while the comment about chasing down the vehicle that supposedly crossed the centerline was unnecessary, it would have been the only possible way to shift responsibility from you to them. (Of course you would need to have them admit to the authorities they ran you off the road even if you caught them...like that would ever happen)