Here is a list of some chocolates that may be more available in your area.
Making chocolate is easier if you start with unsweetened baker's chocolate (which is dairy free)
How did you try to make it?
Coconut oil and cocoa powder would work too- but you need a LOT of cocoa powder. Chocolate also requires some form of sugar and often salt to bring out the flavor. Many cocoa powders, however, are just bland- you have to start with the right cocoa. I suspect much of it is effectively stale.
As to Maltesers... it won't be an easy matter to make that fluffy core.
That's a matter of specialized equipment.
You may very well need to rig a vacuum chamber to fluff it in.
I'd try using a whipped cream charger on a mix of coconut oil (maybe 30%) and super-saturated melted malt.
Then transfer it into a home made vacuum chamber and inflate it (and cool it) as much as you can.
Something like what this guy is doing:
There are a lot of different configurations that can create a vacuum chamber.
I'm sure you can find instructables on that.
You'll probably have to spend $100 - $200 though, on building one.