I heard from other mums if your maid wanted to borrow money from the loan shark. The loan shark will call her employer to find out if she works in your home. If the employers say she is (or she is not) at home. Which means that the number that your maid gave to the loan sharks is true. Your maid will get the money from the loan sharks. So other mums advised that if any local HK people calls your maid. Tell them that no such person or wrong number.
Is your maid a Yan or Bun? Does she have her own cell phone? If yes, why someone calls her at your home number not her cell phone? If this is her client, I don't think he will call her at your home for "business" .
My new bun only worked for me for one month. This is her first time to be a domestic helper working oversea. She had her day-off last Sat to meet her agent in Central to pay for her 10% (HK$300) fee. After that, she told me that she met a few buns in Central asking her if she wanted to borrow money. My bun said she already borrowed money in Phillipine so no need to borrow money here. She went to the "financial company" with other buns and saw a lot of buns there. I was so worried after I heard from her.