This is a very common problem, it happens a lot often when people new to hamsters have been given poor advice on suitable cages for hamsters.
Neither tubes or multiple storey cages are suitable.
The problem with the tubes is that hamsters, especially new & nervous ones, will eat, sleep, hoard & pee in them which quickly creates a very unhealthy environment so the tubes need to be removed immediately.
Also if the hamster hides in the tubes it can make it very stressful for both him & you when you need to get him out.
Hamsters need one large floor space, they are ground dwellers, with one large space they can have areas for different uses which doesn't work with multiple levels.
They need a large house with no base on deep substrate which is usually difficult to do with this type of cage too.
The best thing would be to get a new cage & start over, if you can remove the tubes for now& use stoppers on the holes then I would do that.
The best cages if you're in the UK are available online from
Zooplus, the most popular cages are the barney & the alaska.
Some people also use the Hamster heaven cage but I think it's more suitable for dwarf hams than syrians & is best used without the penthouse & tubes.