Hi There,
Using any kind of wax on a matt or semi matt finish is strictly a no no, because you will add extra gloss to the finish very easily, and it's hard to reverse that effect once you've done that.You could wipe the finish down with a wax and grease remover like prepsol from ICI for example. That will strip away the wax and not harm the finish. Don't let the wax remover pool at any stage though.That process done a couple of times can help to reverse the glossed up unwanted result. Running a 4000 grade Abralon pad carefully, gently and evenly over the finish can help to bring the finish back to a matt look as well in worst case senarios.
To maintain these matt type finishes which are fairly delicate by nature, all that's required is to wipe a very moist clean chamois over the surface and finish off with a dry lint free rag like a soft microfibre cloth.
If there is bug splatter or crap on the surface for example, you could use a product like glass cleaner first to soften and remove the spottting, and then follow through with the chamois and dry rag again. Don't let the cleaner sit or pool on the suface for long as that could etch into the matt finish. Strictly, do not use any abrasive material on the matte finish as it will ruin the finished appearance.(abrasive liquids, pastes, or rags etc)
If bird crap or tree sap or tree gum has landed on the finish, you're in for trouble, as the acids and chemicals in these types of fallouts agressively attack the matt finish quickly and etch into the paint finish and cause a visual defect to the finish.
If the matt or semi matt finish was sprayed in 2 pak black or clear, the finish will be more durable to wear and tear in regards to fallout attack problems, and damage to the finish in general. Hope that all helps,
Greg.