Lenz grants you a warranty of 24 months from the date of purchase. You can find the detailed terms here. Please note: Complaints based on slightly different charging states of lithium packs in the Lenz heat app in charging or heating mode are excluded from the warranty. Lithium packs and heating elements are naturally subject to production-related tolerances. These differences have no noticeable effect on the heating performance and heating duration of the product. To make a warranty claim, you can send the product to Bergfritz or directly to the general agency of Lenz in Switzerland. Please use the form below directly: Download Lenz Warranty Claim Form If you don't have the invoice anymore, send a short request to our customer service and you will get a PDF copy.