Samsung DV70F5EOHGW bad design heat pump problem

We bought a 7kg Samsung Heat pump tumble dryer nearly 2 years ago. It worked fine until it became very noisy a few months ago, until we could not use it anymore because of the noise. Still under warranty we called Samsung and they sent an Engineer. He looked at the drum first, which seemed ok. Then he looked into the hole with the Heat Exchanger and he saw that the very soft mini radiator style bits look a bit bent. My wife told him that she regularly cleaned it with a vacuum cleaner with soft brush. This is exactly what it says in the manual. The engineer suggested that this should only be cleaned with a sponge, which is not in the manual.
After that Samsung concluded that they cannot repair the machine because it has been damaged by the user whilst cleaning. All our protests have failed because it is always down to this engineers report in the end.
I believe that there is a design fault. This Heat Exchanger is very soft and you are supposed to vacuum clean it every month, otherwise it will get completely clogged.
I have noticed that other manufacturers have a completely removable unit which can be cleaned much easier. Even when I searched for samsung parts I came across a heat exchanger for one of their newer models which is designed this way.
How can I proof that our dryer has an unusually weak part and there was no misuse from our side.