Personally and you can check my threads on this... WAD id avoid and id avoid Simply Alfas also...
I can not recommend NJS Autos in Pershore enough, those guys are awesome, have a chat with Neil there and he will look after you, he's worked on my 156 loads and makes it feel and look brand new every time.
Also he races Alfas, Owns 2 red 156 racecars (usually sat outside his unit - so is worth just going to oggle at those) and his repairs/services etc are speedy to say the least... his guys know how to do things and the best ways to do them. And ive never ever queried the costs.
I personally wouldn't go any where else. In Fact im upgrading to a Brera in the next couple of weeks and it will go strait to Neil for a once over.
Edit... If i lived closer AutoLusso would be my other choice for sure, never heard a bad word about them. Word up AutoLusso Yo!