Unfair treatment

I register last year for a national certificate and being my first time studying with I'd call if there was something I wasn't sure about. So I called them to find out if I'm supposed to write 2 assignments or 1 assignment because I wasn't sure and a student advisor told because I'm doing a national certificate I'm supposed to write only 1 assignment. So I only wrote one assignment. Now it's exam time they saying I was supposed to write both assignments and as a result I won't be able to write exams for some of the modules. Mind you, I paid in full so I dnt owe them any and now I have to re register for the modules I won't write exams.