The Alaska is on Zooplus and they have a good range of Hamster cages. Everything hrl says is true. Hamsters do best with a large continuous floor area rather than smaller levels - it gives them space to roam and dig. Also the cage needs to be big enough for a good sized wheel (27 to 30cm diameter for a Syrian). We had to upgrade our Syrian shortly after we got him when I realised how cramped he was (and getting stuck in tubes!).
The other thing is having a deep base on a cage, so there's a good depth of substrate as they can then dig tunnels.
RSPCA minimum recommended continuous floorspace is about 80cm by 50cm but basically as big as you can fit in! And a number of people have the 100cm Barney from Zooplus, which is a great cage for a hamster. 100cm sounds big but it would fit on top of a chest of drawers - doesn't matter if there's a bit of overhang at the sides.
So yes it would be a much better investment to get a new cage that's a good size floorspace, rather than another level for the Imac Fantasy. The cages may not look as fun, but they can be made to look fun
Check out the 'lets see your cages' thread - and they are much better for the hamster.
Bar chewing is often because the cage is too small and they're trying to get out! And a sign of stress. Ours did it at first and stopped when he was in a bigger cage.
This is the Barney cage. Comes with a good big house (photos of Barney and Alaska below - the first one is the Barney).
Barney Pet Cage | Great deals at zooplus!
This is the Alaska - second photo below
Alaska Hamster Cage | Free P&P on orders £29+ at zooplus!
My cage is a similar size to the Alaska - 80 x 50cm, but a bit lower, and I wish I had got a 100cm one - once you get Syrian sized stuff in it, it soon stops seeming big and I reckon Charlie could do with a bit more space. Although I do have a big wood house in it (which he loves as it's dark inside! And has space for his hoards and potty).
His house roof makes a shelf and I tied the cardboard tube to the top of the cage so he could get from the house roof to the rat sized sputnik.
This was how it looked a year ago
This is how it looks now (wheel broke and was replaced with a ginormous one because he is a huge hamster lol) and house changed.