It's not the same type of service as Royal Mail at all. Think next day or same day FedEx. They just send everything in one secure vehicle at the end of every day. Remember they are dealing with very valuable items all of the time, so it can't be anything like Royal Mail.
Well, of course. The all-black helicopter with Montblanc star livery lands in the park across the street, and men in up-to-the-minute-fashionable black suits with black accessories and dark sunglasses jump out, carrying briefcases with a chain-and-handcuff so they can't leave them somewhere by mistake. They quick-march in, pick up the items destined for repair in Hamburg, fly to the nearest small-craft airport, then take a similarly all-black with Montblanc star livery business jet to Hamburg MBHQ. From the airport at the other end, transfer is by armored car with special police escort.
The process is done in reverse to return the valuable items to their anxiously waiting customers.
"Only the best is good enough!"
-- Joel -- "I collect expensive and time-consuming hobbies."
INK (noun): A villainous compound of tannogallate of iron, gum-arabic and water,
chiefly used to facilitate the infection of idiocy and promote intellectual crime.
(from The Devil's Dictionary
, by Ambrose Bierce)