Sennheiser Headphones IE8i and Momentum True 2 Failed and Support Was Unresponsive

They said Sennheiser is a good brand, but both of my headphones are defective. My first experience was with the IE8i headphones. I used them for only one year before they started having connection issues, the sound failed, and the cable seemed faulty — now only one side works. Then I bought the Momentum True 2, which was supposed to be great, but it also had connectivity issues. Even worse, while changing the ear tips, the top of the earbud came off. I’ll share a picture as proof. It feels like they gave me all the defective products. I wouldn’t be this upset if I had bought regular headphones. They were supposed to have good sound and bass, but even that was disappointing. I called the company several times and filed complaints, but no one answered or followed up despite saying they would. Time has passed, and I still have no solution. I don’t know what to do. How can a German company be this bad? If anyone has a solution, let me know because I’ve given up on expecting help from the company.