There are two issues that would concern me here
One is that the car crashed into the porch which , if it was added to the building after the house was built it is possibly not of as strong a structure as the main building, and looking at the damage to it I would think that is the case
Secondly, if this happened at the weekend I assume you have only spoken to the insurance company on the phone and you Havnt had it inspected, or had a quote from a bodyshop yet.
If this is the case how can they possibly assume it is a write off