"And it really should not matter where I bought it"
I totally disagree with the above. It's imperative, let me stress EXTREMELY impertative, in this situation.
Since you wrote the above, I am assuming that you did not buy your Langes from this particular Lange Boutique. And just because you are a customer of the BRAND, you are NOT a customer of the BOUTIQUE.
Customer service, in my opinion, goes to where you purchase your watches. So if you did buy your Langes from this Boutique, I would expect them to show you good customer service and offer you a free strap because you ARE a customer of the store.
You cannot expect good customer service from any establishment where you have not established a relationship with them. If you haven't bought anything from a store, do you really expect to them to bend over heels for you? Absolutely not.
If I'm a customer of Ferrari and bought 100 Ferrari's from other authorized dealers and secondary dealers and also through auctions but I didn't buy any car or anything else from Store A - and then I go into Store A and tell him "Hey, I was here last week and bought these rimms from you but I changed my mind. I know these rimms are used but I want those other rimms right there instead." What do you think Store A will tell you?
My 2 cents,
Anthony