As much as I love my Lunova Day/Date, I cannot say that Mühle Glashüttte's customer service is good, rather it is severely lacking in my experience so far.
Two months ago I sent them an email about a new strap, it took them two weeks to respond. I can understand that, it's not a high-priority request.
But more recently I emailed them about a warrantee / guarantee issue with the movement and have not heard back from them for two weeks.
I know that summer in Europe often means companies suffer from being short-staffed as people go on holiday, but two weeks is a very long wait for an answer, unless the whole company closed for the summer (in which case, an auto-reply would be helpful).
I'm a rather dissatisfied customer at this point.