Multiple Yelp Reviews...

Hey, I recently had a horrible experience at a local supposed upscale restaurant. It was for my cousins birthday, there was a party of 20. We all had a horrible experience with the service and we were overcharged. Everyone was charged an additional $35 that was agreed before hand not to be included. I just found out that we were overcharged and am furious. I wrote a review on yelp but it had no effect on their rating obviously. How can I get 19 unique reviews on their yelp site to share this experience?