There are a number of other similar refrigeration products to your wine reserve. The main difference I see between them is the wine reserve has no fan to circulate the air within the cabinet as the other fridge designs do. So that means the cooling is gravity based (ie. Hot air rises).
I seen this reference in a manual:
In general, temperatures at the bottom of the cabinet will be cooler than temperatures at the top of the cabinet. Position your wine inventory accordingly (i.e., white wines in the cooler zones and red wines in the warmer zones).
On versions of that model that I could find, the cooling coil is towards the bottom which would keep the coldest air down there. Warmer air (relatively speaking) would migrate go to the top. If there is a panel between the compartments, that would hamper the mixing of air even more. I do not know how the top would be temperature controlled. There might be an air damper but none are listed in its parts list.
Ideally an internal fan would at least be needed to circulate the air evenly, to create more uniform temperatures.
If it's new, take it back and buy a mini-fridge instead?
JMO
Dan O.