Have you ever taken any courses or workshops related to customer service or sales?

"I've never paid for any courses or workshops because I usually can't afford them. Instead, I go to the library and take out books about customer service and sales. Recently, I read one written by TG Kong, and I learned a lot about sales. For example, I learned to consistently think in terms of how something would benefit the customer. This helps me guide the customer towards a solution that they'll be satisfied with and even opens up the opportunity to introduce services that the company offers. This way, a customer service calls can transition into a sales call."