Sounds a pretty odd one I know!

a friend just "happened" to leave a can in the passenger footwell, which just happened to explode, thus coating me and the glovebox, dash and centre console. Because it was late I didn't sort there and then and it has dried in. I hit up halwelikecarshonestguvnor£40foramotorcyclebatteryistruehonestfords and bought some dash cleaner. It's turtlewax stuff and looks awesome when freshly done, but after a few days it goes dull and the, ahem, "stains" are back.
Long story short, what would be best for long term result?