Hello ,
I am very sorry you have had issues with your Grohe product. The written warranty is below. After years of use there is a time that the manufacture defect ends and it becomes the wear and tear.
Grohe provides a Limited Lifetime Mechanical warranty to the original purchaser when sold and installed in a residential application after January 1, 1997.
A Limited Lifetime Mechanical Warranty is provided on all mechanical parts to be free from manufacturing defects in materials and workmanship under normal use for as long as the original purchaser owns the product. Proof of Purchase ( copy of your original receipt,purchase order or invoice) , the date the product was purchased and installation date is required.
At the company's discretion, Grohe will preplace any part that proves to be defective in material and/or workmanship under normal installation, use and service. Please note our warranty does not cover normal "wear and tear" to your product and we do not cover installation or any other labor charges.
Thank you for choosing GROHE.