Zapper Money taken and not returned!!!!

I have also sent tons of mails to Zapper, my Zapper screen went red saying unsuccessful transaction or something when at a restaurant, then the money was taken from my account but didn't reflect to the restaurant. I then had to pay the same bill with my card, it's been two months now and no response to my mails, nor my money returned. The irony is my clients, who are restaurants ask me if they should sign up for Zappers services, what am I supposed to say when I have this experience using it?