I have a Maxi-Cosi Quartz 360 car seat, bought mainly for the turning functionality. However, the button to release/turn the seat has stopped working, so it's now like an ordinary car seat.
I've been in contact with Maxi-Cosi, who just send a generic email asking for serial number etc. which I have supplied, but then that's it, they haven't replied to my emails chasing them up, their online chat just sends to same generic email, it as if they just don't care.
I've since read a lot of dissatisfied reviews, not to mention safety concerns with some of their products.
There are lots of bad reviews on their own Facebook page, it seems they don't respond to any of them.
I think it's appalling that a company can be like this when their products are supposed to be trusted to keep children safe!
NOTE FROM MNHQ - TITLE EDITED AT OP'S REQUEST