I am sorry to hear about your accident. Unfortunately, they happen to good people, and there's nothing you can do about it. From reading your post, it sounds like there's a lot of damage to the car, and frame damage is costly to repair.
I too, was in an accident 2 years ago, with a Honda Accord, and it had front frame damage. The body shop wanted $6k to fix it, and sadly, I had to part with it.
I don't want to sound harsh, but it sounds to me as if your car is in bad shape, and the cost of repairing it can easily surpass the value of the car when frame damage has occurred. One thing to do is to perhaps start looking for another car, just as a back-up plan and hope and pray that you'll get your car back repaired.
One thing to think about is that with that much damage, it's quite impossible to have your 400E drive the same as before, even if you had it fixed. ( I know, it's a sweet car.........)
I really hope to hear that things work out. I'm sad to find out a fellow Benz driver is in despair.