I've had some great success with the chat function. Questions answered promptly at the Courtyard Sha Tin and a request for a shaver delivered to my room successfully completed at the Aloft Guangzhou.

On the other hand, I've had zero response from other hotels.

So I'd say it's worth trying it and giving them a few minutes to respond. And if not then there's always the creeping horror of phoning the hotel and speaking to a live human being.