I do take your point… but.
Perhaps before the dealer sells you the car, tells you all the positive things about awards and 7 year warranty etc etc, and takes your money they should read you a disclaimer that says; just to let you know that in the event you have issues we are hung out to dry by MG and you’ll be passed from one to the other with no real ownership.
And dealers can indeed offer good service (or at least much improved) by firstly communicating well with their customers, even if MG themselves are not that helpful, customers will respond better to being kept updated.
As you will guess, I have little sympathy with dealerships and passing the blame