Please guide about transfer..!

Hey,

There is one situation,

An article assistant wants to take tranfer from his/her existing firm because he/she is not getting quality work to do and he/she wants to learn more as per his/her interest. But The Principle ( CA Firm) is rejecting to give tranfer or say being late to sign tranfer form.

Student is very upset and confused as he/she is westing his/her time. The Firm is intentionally harrasing the person.

What to do..? What step can be taken against firm..???