job duties not stated in my employment letter.

[cs4_sasi]

I worked as process engineer for three months and got layed off. the employer is refusing to add the job duties to my employment letter. HR is mentioning that since I was in training I didn't have any speciifc duties and cannot provide them. Can anyone let me know what to be done. I have the offer letter, ROE, paystibs and the email memntiong the reason why job duties cannot be mentioned.