Rediff.com / Hometheater 1800w — fraud and misrepresentation

I purchased a hometheater system from rediff.com in their advertising is was shown that it is 1800w hometheater system but when i received the product and plug it in my laptop the voice was so inferior i think it is not of 100w i have a 890w hometheater system that is so good in comparison of their produt i think this is nothing they cheat with me i request you please take strict action so i can refund this inferior product and get my money back it was worth 789 Rs/- with shipping and Order No is- 5166445. please Sir help me.