@yennywee,
I've heard of Taxpayer Identification Number and Individual Taxpayer Identification Number, but tax file number is a new one to me. What country is this?
An outside contractor would definately be withheld at the highest rate if it failed to furnish either a TIN or EIN. An employer would be required to have a social security number for every employee, so I'm not sure of the situation. If in the US, did you refuse to complete a Form W-4?