New rescue Serbian hamster

[Zizou]

Hello I'm a first time hamster owner and have a very friendly hamster from a well known rescue, he is believed to be one year old. I'm quite upset because I got the qute hamster cage from omlet and the rehomeing place said it would be fine for him,I've since discovered that hamsters need more floor space and this one has two levels it's such a shame because it would be great if it was longer in length.you see I trusted what the rescue told me. Do you people on here think I should try and get another one although I've looked and they all seem a similar size. Look forward to hearing your thoughts thankyou