DTG. I have one question. Why have you set the class 101 to £25? That costs more than some routes, and even the same price as the game, and all you get is a train. I know I shouldn't say this, but that's a rip off.
DTG store apparently lists it as normal price. Edit; it's not even listed on the store, it's advertised but clicking "view product" took me to a 404 screen.
There is another link that takes you to the right page. But I am hesitant to get it there because it is not instantaneous like Steam. I once had to wait 2 full days to get a product key.