That`s the problem with these over-priced modular habitats. They are very expensive yet don`t reflect what a hamster needs. They are modeled on a hamsters underground burrow chambers and not the actual space that the hamster needs to run around. Placing a few of the smaller pods inside a larger cage would still alow the hamster to use them, but not be so restrictive because the hamster can then choose to come and go as it chooses.
If your cage is from Pets At Home, they would refund you for it, so do consider it.
Just say that you bought the cage because you were advised to, but now know that it is unsuitable. This happened to my nephew. He purchased a Gerbilarium from Pets At Home and had to return it due to a broken poke in the upper barred section and they sold him a Rotastak Space Command for a SYRIAN?
They don`t stock decent cages in their stores now sadly, so a refund would be your best option.