My LOWA boots are defective, but I'm not certain if they're qualified for an authorised claim under the conditions of the warranty.

Please take the boots to your LOWA retailer to ask about any possible defects. The staff will handle all inquiries and returns. And don’t forget your sales receipt. You can, of course, go to any authorised LOWA retailer, but it’s best to go to the store where you purchased the boots. With their expertise, the retailer can best judge what the best solution is, for example, if your boots should be sent in for repairs.