This case study outlines how HMV, a prominent UK music retailer, successfully reduced its Meta advertising costs by 60% through the implementation of advocacy insights. The document details the challenges faced by HMV in acquiring new first-party data, particularly in targeting new customers while maintaining cost efficiency in their paid social campaigns. It highlights the difficulties of reaching potential customers without overlapping with existing subscribers, which often led to inflated costs per lead. The solution involved the use of Mention Me's Audience Builder feature, which allowed HMV to refine their targeting by excluding current mailing list customers and focusing on lookalike audiences based on their most effective referrers. The study emphasizes the importance of referred customers, who tend to spend significantly more in their initial months, thus presenting a valuable target group for HMV's marketing efforts.