Do More Than Client Expects
If your product is really good then little problems with it will be just a bit of misunderstanding. Customer sees how much you have worked to exceed his expectations and assumes that you will improve. If you create a product just like everybody and nothing more then you do not have enough excuses to close the holes that discovered by your client . And he will stop believing that you are friends .
There are many good examples on the topic: one guy lost an adapter to Bluetooth- mouse produced by Logitech. In response to his request on company's forum, where he can order such adapter, the company just sent him a new one. This created a wave of comments and feedback regarding the case and Logitech's reaction. This is an example of creating customer loyalty.
Another example is the Apple tech support in America - its famous experts (via social media) have a massive knowledge than they need and even more to do their job. They do not have a pleasant female voice however solve problems of their customers really quickly.
Before you start fighting for customer loyalty, create one in your company
As a rule, people serving customers from call centers or from technical support side are rarely valued within the company environment. Make them first and important in the eyes of customers. Give them more authority to solve problems. Building an attitude to those people in the company is seriously important: respect from co-workers and customers will help those people to become more proactive and effective with their job. That will help a lot to build a perfect customer service. Feeling like a part of the same team and experienced for their pride, they will try to do everything make the client happy.
If possible, let your employees use the product they sell and serve. This will help them to give feedback and confirm the benefits of the product.
Have Sense of Humor
Technical support team for online poker Pokerstars once received an e-mail: " Don't you know when Jews celebrate Easter? ". Rather than ignoring a non-poker message company specialist spent a bit of time researching to find an answer to the question. This turned into a very amusing customer conversation thread and created a great feedback from customers and the support team was answering all the e-mails and following all the forum conversations.
Smile while answering the phone and calling to talk to your customers. Smile can be heard. That is true.