[Ria P]

Hi, unfortunately this happens quite a lot that pet shop staff sell cages that aren't that suitable. I'd try and return this cage and get a bigger one. I don't know how big or small it is but your hamster isn't happy. Until you get a bigger cage sorted you could put in as much substrate, paperbased one like Carefresh or Kaytee clean & cosy, as possible so your hamster can burrow. I'd take the house off the shelf and put it on top of the substrate so he can make a nest. Tear some plain white toilet paper into strips and leave it next to the house. You can put a cardboard toilet roll in for him to hide in and chew on.
Some people make a bin cage out of large storage box which requires some DIY to sort the ventilation or a big enough fish tank with a DIY mesh lid can be used too. That way you don't have to worry about escaping. Have a look at the thread "lets see your cages" on the Forum under Housing.
My Robo lives in a fish tank which isn't the ideal size because a bigger one would be better but here's a photo anyway so you can see how much substrate they need to burrow and make tunnels. He's in his house just now and probably dug himself in. They need places to hide and feel safe in. It looks like your Robo hasn't got that so tries to escape. He should settle once you provide him with what he needs.
You've done the right thing by joining this forum. I've learned a lot since joining this very helpful site.