Customer service is a significant factor in creating brand value, however it is still poorly understood how it relates to customer behaviour and efficiency of a company’s marketing funnel. The paper attempts to examine this relationship within the Fintech industry. Methodologically, the study rests on the postulates of marketing theory on customer experience management and a company’s brand value co-creation. Among the research methods is primary data statistical processing through the A/B testing. Empirical data come from a Nigerian fintech company’s internal reports on customer behaviour and cover information collected by customer support. The A/B testing on a sample of 1,964 customers showed a 14.2% conversion in the test group provided with a tailored customer service, which is 3.96 percentage points in absolute terms, or 38.7% in relative terms, higher than in the control group with a conversion of 10.2%. Our experiment demonstrated a statistically significant difference (97.7%) between the groups, thus demonstrating the effectiveness of the targeted customer service in improving customer conversion metrics. The theoretical and practical findings confirm the hypothesis that customer service is a co-creator of brand value, and this impact can be utilized to enhance the efficiency of the company’s marketing funnel. The authors plan further research into the applicability of the methodology to customers in other countries and sectors.