Bests & Worsts Reviews from Amazon

I deliberated on buying a new chair after my last one broke for a while. I wanted one that was comfortable as well as strong, a chair that'd be durable. I ordered this chair and I assembled it perfectly, it was great, so comfortable but 2 weeks in I come to find the chair tilting a bit. It turns out on the central seat plate (the part you screw everything into in order to secure the chair) has a plastic base and one of the corners cracked. Now let me also clarify that this chair is supposedly rated for 400 lbs (which I'm well under) I asked for assistance on this and all they could do for me without fully disassembling and returning the only office chair I have left after going in on this was a 30% discount. There's no parts service or anything to assist with this. No warranty help from the actual company unless I go above and beyond out of my way to get some kind of help, and that's even not a guarantee. Naturally I'm a bit disappointed. It's supposed to be a high quality material chair, WHY is there plastic on this seat base? It tilts and creaks moving it now, it's still usable and comfortable, but it had serious issues come out in just weeks on a chair that's supposed to be highly durable.