USA Reward Spot review: unfulfilled gift cards for surveys

I have completed over 3 dozen surveys, and made final "Silver" purchases, only leaving me without a promised Gift cards. This happend 4 times, over the past few months. They keep sending me different amounts for gift cards. From Walmart $500, to Target and many others. I cannot contact anyone regarding this. Many hours of surveys and broken promises is all I have gotten from this company.