Hi, If anyone can help, I need clarification on the amount of tax I should be paying -

I work once a week, for 8 hours, I get paid R80 per hour, so that is R640 a day,
This month I made a total of R1860, and have been taxed 25% (R470)
I am NOT a temp worker, although I may be considered a 'casual' employee.

The reason that they give for such a high tax, is that apparently, if you are a student, working less then 22 hours a week, then you will be taxed 25%

Is this true?
I cant understand how I can be paying such a high tax, on such a small amount of money?

Thank you.