Mirra chair's armrest gone all puffy. Warranty advice.

I have a one year old Mirra chair (my back absolutely loves the chair). It has like 6-12 years or so worth of warranty/guarantee. The armrest has become all puffy internally. What I mean is that the armrest has an internal padding and then on top of it is fake black leather covering which I assume was either internally glued or very tightly wrapped/pressed over during manufacturing. Now the armrest is full of air pockets between the exterior fake leather layer and internal padded material. It’s irritating when I place my arm on it. It’s all dimply with air.
I contacted the place where i bought it from and they did not reply to my e-mail. I am planning to pay them a visit but I wanted to run by you if stuff like that should be covered by guarantee? So to sum up, the armrest is in no way cut or damaged externally but internally poor manufacturing process has resulted in my puffy armrest problem.

This armrest bit is what I am talkign about-

Should definitely be covered under warranty. Try HM directly if the retailer can’t be bothered.