How much more would you be prepared to pay for 'almost instantaneous' email support? $50/€50? The answer can't be zero - support is expensive to provide and what you're experiencing is the level of support that can be provided by whatever % of the Davis margin is currently allocated to support.
But, as has been mentioned repeatedly, support outside the US is officially provided by the supplying dealer. If you do hunt out the very cheapest pricing eg on Amazon or wherever then it's almost inevitable that the support provided will be minimal - there's no margin left to provide much support.
All that said, I am surprised that Davis have not come back to you - this is a potentially significant issue. Maybe they're discussing it internally and you still might receive an answer. But it may also be a classic support issue that you have to get past frontline support and talk to someone more senior before they recognise its seriousness, which is easier said than done, I know (unless you have other contacts within Davis).
Reflecting on this further, I do start to wonder whether this isn't 'simply' a faulty logger rather than anything more suspicious and a replacement logger might work fine. So the rather unsatisfactory answer given the lack of response from Davis might have to be going back to wetterladen. (Not much consolation I know, but if this logger had been bought from us and shown the same problem then we would have replaced it immediately just as soon as we had confirmed the fault here. And would also be pressing higher up in Davis for an explanation.)
If that's the issue, mailing someone with "contact the supplier" is not that expensive. If they cant provide it for free don't anounce it as such. And yes in my opinion should be almost instantaneous, at least within 24 hours even though i patiently waited more than a week before mailing them again. It's not a crime but is it a poor service? Yes.
I've worked in a technical support. One of the first rules i was told was never leave the customer alone, never leave him with no answer if you do not know the answer or cant help redirect to someone who can or come back with the solution later.
I payed 80€ for 3 years for a webhost and a domain and i've tech support 24 7 and it is instantaneous at least via email. Yes, it's a different kind of service, but they feel responsible for the money i gave them and wasn't more than 1000€ like Davis.
But that's not my point because not every company can have a great service. I just think there's no excuse to leave me with nothing, if this issue can only be solved by Wetterladen then they could say it. And i did agree with your opinion, because if i can get Davis tech support why not? theoretically should be the best support there is for their own products. As they say if you're outside US you can contact them or the supplier.
Yes this might be just a faulty logger, i understand there's time, costs and other issues involved but i just simply wanted a reply even if that was "we cant help you".