Since no-one else has posted to this thread, I'll just add something of my experiences of dealing with Charles Warner, Lincoln.
Over something like 20 years both my wife and I have bought a variety of different cars from this company, including Vauxhalls, both new and second-hand (they used to be Vauxhall Main Dealers) and, in 2015 a new MG6 TL (which I still have), with an MG5 LR Exclusive on order with them, likely to be delivered in March next year, apparently.
Over that time I have always been impressed with their willingness to be as helpful and accommodating as they can be to me, as a "long-term/established" customer. I have no idea to what extent my experience would have been different if I were not such a customer but, over the years I have developed a relationship with various members of their staff which is both business-like and personal. Yes, there have been times when I felt somewhat "aggrieved" about my MG6 (e.g. whilst on my way to a family holiday to France, the near side front window developed a regulator fault - they're electric - and the window could not be closed. On return to the UK Warner's Service Manager persuaded MG UK that the repair should be done at MG's expense, even though the official warranty had all but run out.)
Overall, to date, I'm very happy.