True sales are all about partnerships and collaboration. Tap their knowledge base and let them help you gain information. There are many books written on this topic. I don't know what's causing it, but I've noticed an increase in the number and frequency of verbally abusive customers. These are stressful times we live in.
People are hard-pressed to get more done is less amount of time.
Many people are sleep deprived and this can cause short fuses and temper outbursts. With the added stress, there seems to be a general decline of manners, civility and politeness. Ask the offending individual to step away from the public area. If at any time you feel you are in any type of danger or that the offending customer is on the verge of becoming violent, remove yourself and call for assistance from law enforcement. Customer service strategies are thrown out the window if there is any risk of bodily harm.