It's strange how companies think they can just send customers to the endless loop of voice mail trees, and how agents who never go off script can produce any kind of loyalty.
It's simple: being polite and professional is always appropriate. Add to that a willingness to go above and beyond in order to make sure a customer is happy and you probably have loyal customers.
I like to visit a fast food chain in my town because the employees are always pleasant. They seem to be glad to see me. I'm not just another animal coming into the pen that they have to deal with. It makes a huge different in the way I feel about that company.