I feel for ya Mate!! Body shop's not pleasant place to have to send you New motor, specially when it's not your fault.
I guess your Insurance will pay up & recover the money from their insurer, when i had my prang (which was my fault) the Garage collected the car the next Morning & repairs were authorised the same Day, they do seem pretty good now (depending who you are with).
Anyhow, it looks like straight replacement job so no knocking it about!!!