Customer service is not usually thought of as sales. In fact, it is a huge part of sales. Most, if not all parts of the company are involved in sales, whether they know it or not. Since customer service is usually the first group people talk to, unless it is salespeople, it is important for customer service people to sell the company well and help the customer.
Building relationships and finding out what the customer wants is a very important part of customer service, as it is with all salespeople. Customer service people are there to serve the customer. They cannot do that very well if they do not know what the customer needs help with. Good practice is to take time listening and asking lots of questions to fully understand the situation. It is also good to repeat back what the person said to make sure you understand it correctly. Building trust is also important in the process. This can happen quickly, but it can take time to build a strong trust in a company. If a company does exceptionally well with this, it can receive some recognition. Someone might tell a story of how the company went out of their way to help them, then that friend will look into it and/or tell more people about it.
Zappos is an excellent example of a company with excellent customer service. Generosity and customer service is part of their sales formula. They treat customers very well. There are many stories out there you can find about Zappos customer service. One of these is that the customer was feeling hungry and told the Zappos representative, and they went online and ordered him a pizza and had it delivered. A story like this definitely gets attention, which in the end will hopefully grow the business.