@Gareth237
Sorry to hear that. When I read this guest's review, it just makes me think he's a miserable person and a pendant. For example, it's pretty clear from the listing photos and description that the unit doesn't contain a living room so, if that's something he needed, he should have booked elsewhere. Likewise with the freezer. I don't know how long this guest was staying for but really, who complains about the size of an ironing board?
Unfortunately, we do get these sorts of guests every now and again and even one low rating can jeopardise Superhost status if you do not host large numbers of guests (this has just happened to me after 5.5 years of being a Superhost).
Unfair as it seems, you just have to take a deep breath and move on. As @Kate867 says, the review doesn't violate the content policy so it's highly unlikely that you can get it removed. However, the whole review reads like it's from someone just looking to complain. As a guest, I would pay more attention to the other, more balanced reviews. This one will soon be buried under more positive ones.