Banking is one of the strongest pillars of the Service Sector; a major contributor to India’s GDP sources of credit to both household and industrial sectors. With the advent of globalization and upcoming private banks in India, there is a significant rise in the customers’ expectations resulting in increase in customers’ complaints. In this context, an effective and efficient “Complaint Redressal System” is looked upon not only from regulatory perspective but also marketing support. Awareness about the functioning of “Complaint Redressal System” by the customer and reaction of aggrieved/dissatisfied customers have kept banks vigilant in the competitive market environment. This research paper is an attempt to study the efficiency of “Complaint Redressal System” adopted by both private and public sector banks in India; the paper also undertakes comparative analysis of banks under two types of ownerships in terms of efficiency in resolving complaints, the customers’ perceptions, satisfaction and rating among these two types. Total 1000 bank customers (500 customers each of public sector banks and private sector banks) are surveyed from NCR. Exploratory research (secondary sources and literatures/review) and descriptive quantitative tools on the basis of primary data collect through survey are undertaken by the researcher. Hypotheses tests are done using both parametric test (Z-test) and non-parametric test (t-test, Chi-square test).