make sure all receipt of money and airfare ticket etc are properly signed by her. Also, make sure that she write the resignation letter (better she writes than you write) and states the reasons of early termination and the date when the contract will terminate. Fax all receipts and resignation letter to the immigration department as well as the consulate for their records and information.
if so, better have a witness to the letter and state also in the letter that she understand the contents of the letter , to avoid any further problem , also in my situation, my agent advise me to fax all receipt of airticket and compensation etc to the relevant authority for their information. I think that is no harm and to protect you as well
She has to write the resign letter because she doesn't know Eng nor Chinese, if you write for her, there may be complication. Then ask your agent to translate her resign letter for you.