They want me to RE REGISTER for the Subjects i did

I registered for a marketing Qualification in 2*** of which I passed all my subject except 1 Subject which is advertising , from 2009 - 2015 I had money issues since I'm a bread winner at home with 2 kids and I couldn't afford to further my Studies with that 1 subject , now this year I want to finish my course and I was told that I won't be able to complete my course I have to re-register AGAIN and re write all the subjects .. ( why) ?? is this how they making money or what ? when you register @ this campus there's no clause which state that if you don't complete your course you are not permitted to enrol again ... I feel that this is unfair and ripping people off I don't want to RE REGISTER for the whole course since I won't afford to do so I want to register that subject I couldn't write the time I was with Boston so that I can't obtain my diploma , they have my record and my results so why am I forced to Re-Register again for the same subjects I did ????? I spoke to pule from Carlton Centre I'm not getting any joy from this man please look @ this as I'm in a process of taking this further I really want to finish my Diploma with 1 subject I couldn't ..