barry - // Yes, I'm aware. The current offer is £800 more than the original, surprising for a 13 year old banger //
If it looks to good to be true ...
As advised, they will bank on the fact that you have arrived with your mind set on selling, not driving the car home again and having to start again, so they will drop the price considerably, and hope you will accept, rather than have to take your car away again.
Not everyone will, but enough will to make the system workable for them.