A very valid point but as someone mentioned elsewhere they are saving £80 a month, hardly a deal changer and lets be honest, you "could" go out, buy a very economical 2nd hand car, use it for 2/3 years and sell it for not much of a loss and it wont cost as much as you have lost on a ev.
You can also discuss future ev costs, they wont be subsidised for ever and then who knows the true cost.