My Grundig Coffee Machine Doesn’t Brew and They Refuse to Accept the Return

We bought a Grundig coffee machine from N11. We opened and tested the product, but since it didn't brew the coffee, we wanted to return it. The seller didn’t want to accept the return because we had opened it and told us to send it to the Grundig service center. After a month, Grundig finally called today and said, "There’s no fault with your device, you can’t return it, we’re sending the device back to you." Let them use the machine that doesn’t brew coffee themselves! There can’t be customer service this bad.