Marks not as per expectation

just got the result of ca finals. 

i just attempted the 2nd group only.was pretty sure that i will score above 50 in each subject but i got only 149 marks.what are the remedies available if i m quite sure that i deserve some good marks.

moreover in NOv 2012 i attempted both groups and scored around 155 and 180 marks respectively.

and this time when i gave just one group and worked hard i got some dimnishing returns what can be the reason.i m quite disappointed with the result.

what should i do?