Can you explain why a new Mercedes was supplied rather than something less extravagant and more in keeping with the customers own car?

Drive Assist has a history of supplying luxury cars rather than "like for like" so that they can make more money out of insurance claims. This is to the immediate detriment of the person whose insurance is being claimed against and to the long term detriment of all of us as it leads to increased insurance premiums across the board.