I just had a good experience with Lynx Diesels in Wokingham. www.lynxdiesels.com
The owner Alan, services and repairs diesel pumps and injectors with a very quick turn around.
I had starting problems with my 2002 525D e39. BMW recommended a new high pressure diesel injection pump, £900 fitted. B*****ks to that. Found Alan on yell.com he diagnosed the problem over the phone. He told me what to test and check. We found two faulty injectors.
I took two injectors to him which he refurbished in less than 24 hours. He also refurbs high pressure diesel injection pumps prices depend on what bits need replacing.
Nice bloke who clearly knows his stuff. Mob: 07908 219 781