When customers are unhappy with your products or service, the person they speak to can make the difference between a happy customer, and an ex-customer. Unhappy customers can soon become angry if they are not dealt with effectively, especially on the telephone. Its importance varies by product, industry and customer. As an example an expert customer might require less pre-purchase service (i.e., advice) than a novice. In many cases customer service is more important if the purchase relates to a service as opposed to a product.