Yes it's better to have one larger continuous floor area than two smaller linked ones, as CMB says. Zooplus have a good range of cages. They sell the Hamster Heaven, but they also sell the Alaska cage which is very reasonably priced and only just over £32. Similar size to the Hamster heaven (slightly taller). The main problem with your two smaller ones is fitting a Syrian sized wheel in. Another option is making a bin cage out of a plastic bin. That isn't always cheaper, but can be if you or someone in your family already has a range of tools.
This is the Alaska cage. The price includes delivery as well
Looks a bit bare on the photo but you can soon add some home made toys, and an 11" wheel easily fits. It also has a good deep base because hammies like lots of deep substrate to dig in and burrow in.
Alaska Hamster Cage | Free P&P on orders £29+ at zooplus!
There are a couple of other great cages suitable for Syrians on Zooplus as well - the Barney and Alexander cages. They are both 100cm wide. I have the Barney for our Syrian as I found something the size of the Hamster Heaven got a bit cluttered with large toys and wheels - because we have a very large Syrian! But the Alaska is a few centimetres wider and taller so a good basic cage for a Syrian. If you had the space and could pay a bit more, the Alexander is a lovely cage and comes with 3 houses and shelves.
Great deals on small pet cages at zooplus: Alexander Small Pet Cage
Barney Pet Cage | Great deals at zooplus!
The Liberta cage could do as a play cage or somewhere to put your hammy when doing a cage clean
You could sell the Rosewood Pico maybe to get some money towards something else. I'm not sure what the bar spacing is but it might be suitable for mice.
Also, some people have been successful taking a cage back for a refund saying it's not suitable or too small, even after using it, so that might be an option if you haven't had one of them very long.