Or you could try cleaning it up yourself, and then buying a dehumidifier. If you live in the classic Chinese apartment it is a big concrete box. Such apartments are susceptible to moisture build up, and in turn mold. That is why you need to get a bucket of water, a rag, and one of those white face masks you see people wear when they are sick, and clean it yourself. Do as little to disturb the mold as possible when you clean it up, then once done, get a dehumidifier to make sure no more mold returns.

People from the west don't understand that most Chinese apartments don't have walls that have "insides" they are just giant concrete slabs, the whole apartment more or less having been "poured". This means no place for things like mold, mice, rats, or insects to hide. It also means easy clean up, and that it's hard for leaks to occur to your downstairs neighbor in times of cheap pipes breaking. What you see it what is there, there is no inside of the wall, no insulation, just a concrete box. Get a bucket, and a rag, and go to work.

Even things like this are not largely understood by Westerners, and it is the simple lack of understanding of even how Chinese construct their homes that can lead to such problems as this. Clean up in your average Chinese apartment is far easier than in the west, where such problems can grow inside walls even when the visible problem is cleaned up. Not a problem here, as there are no insides of the walls or floors to worry about. Hope this has helped. Good luck.