Yes, a bit further out. To be honest this has dented my view re electric cars. I was all for it at first, with us going for a PHEV as a stepping stone to let us get the charging figured out etc. (home charging tricky but doable). Most of our week-to-week driving is low mileage, but we periodically drive ~150 miles to visit relatives and it sounds like we would struggle to do this on a single charge in an full EV.
Give the other dealer a call or request them have a look at it and provide a loan car. Any issues speak with MB.
Some EV’s on the scheme will get you 150 miles even in winter but, if its a 300 mile round journey you may struggle without charging on your return!
I do frequent journeys and currently weighing up EV’s but, truth be told I’m more for some kind of hybrid approach, probably PHEV as Oscarmax.