Start by making certain you have enough agents available to efficiently handle call volume. Then, employ skills-based routing: An agent that is adept at settling customer disputes will be able to handle these types of calls more quickly than someone without those skills. Also, as certain customer inquiries are bound to come up repeatedly, train your agents to anticipate these questions and answer them before they can be asked.
Another tip: collect data during the call instead of after the customer hangs up, so agents can proceed to the next customer more rapidly. Also, make sure agents know the importance of average handle time: one way to do this is to reward those who improve their performance.