Hi! I looked up a domestic helper agency on the geoexpat website and was surprised to find that it had a part-time option at a very reasonable price. I have not tried their service but am intending too. The company is called Homeeasy -
www.homeeasy.com.hk. They even provide a service for those of you who need a replacement helper for whatever period you need. The charges vary from $180-$600 a day.