Have been in customer service for many years. My last corporate job I was employed for was an interesting one. I was tier three. Those clients no one could deal with. I felt a bit sociopathic sometimes. Guys would be ranting and raving and I had the power to terminate accounts. I remember one guy venting, going off. I calmed him down after about three or four verbal warnings and said we no longer want your business Sir. I remember his voice, it was breaking, but the decision was made. You are fired.
But yes, customer service is the most important aspect of your business. If you dont give your employees the right training and support and even motivate your staff ( assets ) to provide excellent service you will wonder why you not having sales. train your staff, improve their conditions, invest in them and you will see your business flourish. But the customer is not always right, I know that for fact.