Currently, financial transactions made through banks are popular form of doing e-commerce and e-business transactions wide-commonly used by people from all levels and classes of society. On the other hand, there is a close competition amongst the banks regarding the “customer service” to attract (and retain) more and more customers day by day. In other words, nowadays customer service has become the key success factor of the banks (whether private or estate/governmental) and not surprisingly many of the banks try to optimize their customer service systems by reducing the number of failures eventually leading to higher customer satisfaction and more customer retention.