Is there a matrimonial site with money back offer?

Yes, there are many such matrimonial sites which offer guaranteed return of money. I personally feel shaadi.com is the best amongst them as it serves you the profiles as per your requirement by allowing filters, chat option and other rich features. If you are not satisfied with shaadi.com match search then if you claim for refund within 15 days of upgrading to paid version then your amount will be refunded without asking a question.