I've never got any spam sms while in China.. and I've been to plenty of places with several phones (Swiss/German/Chinese numbers) - of course besides the "Welcome to China" text messages you get when connecting the first time to their roaming network. As everywhere in the world.

But then, paying to RECEIVE a text? I can send (when in my home country) free text messages world wide, and receive world wide for free (obviously) - what kind of scam provider actually charges you to RECEIVE a text? I would asap change to a provider that isn't scaming you.