Not hi-fi or home cinema but I would like to recomend Norwich In Car Entertainment on Dereham road in Norwich.
A good few years back when I was still at college I was after a headunit for my 1st car (old P reg mini with a mighty 850cc engine). At the time I was just window shopping but looking to buy reasonably soon. I tried the shop just down the road from NICE and was not impressed by their customer service. Took them ages to even notice I was in the shop and then when they could finally be bothered to help me they seemed more interested in shifting their old stock rather than trying to help me decide what was best for me. When I said I was just having a look at the moment they tried to get me out of the shop as soon as possible.
So I left pretty sharpish and tried NICE that had only just opened. Pretty much as soon as I had walked through the door I was given a warm welcome and I explained that I was just window shopping at the moment and trying to find out what my options where. Unlike the "other" shop they where more than willing to show me a few options and I even demo'd a few systems. I must of spent a good hour or so in the shop chatting and trying out various headunits. Considering I was a poor student and couldn't afford to buy at the time I think speaks volumes. Really helpfull,polite and very knowledgable. And they had other customers in the shop at the time.
Anyway I have been a customer of NICE now for a good few years and wouldn't go anywhere else. I've had everything from a basic headunit to the system I have now which has a top spec Alpine head unit,Infinity components up front,JBL speakers in the back shelf, 2x150Wrms JL Audio amp, 1x250Wrms Alpine amp and a 12" Infinity sub. Only recently installed and sounds bloody amazing. I bought the new headunit and the 2 new amps as my old Denon amp had developed a fault after almost 10 years. The JL audio runs the components and the headunit powers the rear speakers. The Alpine amp is only just up to the job of running my sub as it's in a sealed box and trying to get the sound from my 3 series boot into the car isn't easy. They are willing to take back the Alpine and knock the money off a better spec'd amp. When funds allow my car will be going back to NICE for a small upgrade.
Just goes to show what respect for your customers and potential customers can do. I've had various systems from them now in 4 different cars. Highly recomended if you live in the area.