Dun Understand...

Yesterday, I've no choice but to call back the previous company again. I had to get the HR to recall some of my documents at the various branches. Due to the change in the address and company I'm working at, I've got to notify the authorities and to send back some documents issued to me by the authorities in order to get the updated ones. After speaking to the HR came a surprise. HR told me to send in my resignation letter as my termination was changed to my voluntary resignation. THis is just weird. I dunno what's the reason. Maybe they were just trying to get rid of me in order not to pay for my bonus or 13th mth. Or maybe they they were afraid that I'll raise my unhappiness to the MOM? I jus dun understand...