Hmmm...the only ones I've found to be that big are from bigdug.co.uk:
http://www.bigdug.co.uk/ProductDetail.a ... 10&CatID=9
They are rather functional to look at and may not fit well with your decor - my hammy room used to be Will's playroom and is blue so fortunately they go well in there!
The shelves are full adjustable - they come with five shelves but I've just used four of them and this gives me approx 50 cm height between each shelf. They are 90cm wide and 45cm deep.
Try as I might I've never found anything else that size.