Why not keep an existing customer? Acquiring a new customer costs 5 times as much. Customers rarely leave abruptly and give signals that they are preparing to leave. Get those signals and identify at risk customer.
Customers are digitally savvy and expect to do things themselves. A deep knowledge of process, usability, grouping of what belongs together, application design, data privacy are required because an existing application cannot be forklifted for self service. Understand the self service options and enable them.
