Samsung Washing Machine Drum Hitting the Door

I purchased an 11 kg Samsung washing machine four months ago, and it seems like the drum is about to come loose as it bangs against the door. For a whole week, my laundry was stuck inside. Since the month I bought it, I have been calling customer service continuously, and they keep saying there's no problem and that the banging is normal. When the service technician came, they ran a 15-minute short program, measured the noise level, and claimed it was normal. They said it happens in every program. The machine runs very loudly. I am extremely dissatisfied. I don't understand how they can consider the door banging outward to be normal.