Building an accurate, up-to-date list of customers, with telephone numbers and contact details is nearly always a challenge.
It seems self evident that companies should try to satisfy their customers.
Satisfied customers usually return and buy more, they tell other people about their experiences, and they may well pay a premium for the privilege of doing business with a supplier they trust.
Finding that person in customer loyalty research may require a compromise with a focus on one person – the key decision maker; perhaps the transport manager in the example of the trucks.
If money and time permit, different people could be interviewed and this may involve different interviewing methods and different questions.