This mixed-methods case study explores the complex landscape of service provider migration and bank switching behaviour among online banking customers in Harare, Zimbabwe, specifically focusing on customer retention factors. The research, which integrates quantitative data from a survey of 224 customers and qualitative insights from in-depth online interviews with 13 bank managerial participants, uncovers significant relationships that provide actionable insights. The quantitative analysis reveals that higher behavioural intentions are associated with increased switching (t = 3.45, p < 0.05), while perceived switching costs (r = -0.72, p < 0.01) and switching barriers (r = -0.65, p < 0.01) serve as barriers to switching banks. The qualitative findings, on the other hand, highlight central themes such as the paramount importance of service quality, emotional factors like trust and personal relationships with bank staff, and the influence of promotional incentives. Customers expressed that while they value service quality, concerns about switching costs and the logistical challenges of changing online banking providers were significant deterrents. These insights, which have practical implications, provide valuable guidance for banking institutions aiming to enhance customer retention strategies and improve online service delivery. Financial service providers can better address customer needs, foster stronger relationships, and contribute to a more resilient online banking environment in Harare by understanding the complexities of service provider migration.