As far as I know, there are many agent charging abnormal high agency fee from the maid, sometimes over HK$10,000. All HK agency fee (for Philippines maid) is max cap at 10% of her agreed monthly salary. If the agency fee is charged by Philippines agent, the agency fee is max cap at 1 month salary + Phil Peso 5,000.
If the agent call you again, you ask the agent how much your maid owe them. If it is over the said max cap, you just tell me straightly that
1) first it is not your business as you as an employer have paid your agent fee.
2) you cannot deduce the money from the salary as it is illegal.
3) the agency fee is over the max cap. You will advise your maid to file the compliant to both Labour Dept & the Philippine consulate which will investigate the case and legal proceeding to be taken accordingly.