The only thing surprising me is that you'd bring an E60 520d anywhere near a main dealer for a service tbh.....
The newest one is now 12 years old and the old adage of wanting a main delaer service history is a fairly moot point at this stage - I'd much rather see receipts/invoices from a well respected indy with preventative maintenance done (main dealers don't do preventative maintenance by-and-large, unless under recall).
I can also recommend John Roche who has looked after my E39 on a couple of occasions.
As a slight aside, a local guy to me has a 2010 E60 520d that has rolled over 200k miles at this stage on its original chain and he's no intention of changing it (a mechanic by trade) as it's still whisper quiet.....