Hi
I want to ask some question...
I from Indonesia and i have student visa(X) and i want to change to Working visa(Z)...

and i'm working in some company, the think is the company cant provide me any letter or invitation to making a working visa...

is it still possible if i still can change my X to Z? or any solutions to solve my problem? my visa will expired on the middle of April...

The document i have is :

Diploma from my university
And also i have reference working experience in my country for 2 years...

and maybe i still need another document to fill it?

Thanks