International student paying tax?

I am an international student working partime job but I never go over 20 hours. However I am paying tax and my employer states I am being put under emergency tax and the money will be returned but it has been already 6 weeks but the money i am paying for tax gets more each each. I am losing money over my own job and I heard students working will be exempt from tax. I been trying to call HMRC for a week everyday and it cuts me off after waiting for so long. I can't sign up for any self assessment as I dont have any ID that HMRC requests as I am not a citizen here. Please help :(

Hi,

In order to be tax emempt you have to meet the conditions here:

Tax on foreign income

If this applies you will need to contact our Income Tax team to have your record updated. 

Income Tax: general enquiries

Thank you.