It's probably a waste of time trying to call directly. As mentioned here, if you are not based there anymore, you're next best option is probably to have a Chinese-speaking friend in Beijing do it for you.
I had to do the same recently, but as I didn't want to hassle anyone, I chose to go the third-party route instead. There's quite a number of companies that do this you can easily find online. The one I used was quite responsive and wrote decent English (all correspondence was done by email; payment was by money transfer which was kind of shady). It's quite expensive for such a basic piece of paperwork if you ask me, but it was required so I bit the bullet.