Bosch Idos Washing Machine: Post-Service Issue Dismissed as User Error

I discovered that the issue with my Bosch Idos-equipped washing machine persisted after a part replacement by the service. They claimed it was a user-related problem. But then, why was the part changed in the first place? The problem began when the machine was only 3-4 months old, and I was constantly put off, being told it would be fixed. The response from the factory was a disappointment. We purchased a guaranteed and insured product from what we believed was the highest-quality brand, but in the end, we had to find the solution ourselves. I won't forget the difficulties I faced while pursuing a replacement or refund, and I don't forgive this mishandling of my rights. A letter suggesting to change the detergent brand doesn't close this matter for me.