Ca final certified copies

I got certified copies of my ISCA paper attempted in Nov 2017. In that, for 80% of the questions the valuer put correct mark, but he gives only 1 mark or 1/2 mark. On the whole, i got only 30 marks. I thought it is very unfair. There are some questions, for which i have written exact answers, but for those also he has given very less marks. What to do now. Please give suggestions.