From time to time I find myself relying on the advice of a vendor or shopkeeper when buying products or services. It is because I am relying on expertise that I don't have or have ready access to. Electricians, painters and anything to do with motor vehicles are good examples.
If you or your staff are in a position to offer specialist service or advice it is really important that when answering questions the answers are complete and accurate. Communicate anything and everything that a customer should know.
A good example for me was in the simple act of purchasing a light bulb. Because the specific bulb required was made of a particular core substance (tungsten) it was important that it not be touched directly on installation; the reason being that tungsten absorbs the oil from our hands and creates hot spots limiting the lifetime of the bulb.
I did not know this but thanks to an alert sales person I was informed - unfortunately, I did not tell Mrs Bell and I expect to be returning shortly to purchase another bulb. A perfect example of the need to relay the information; and correctly.
My modus operandi when not sure of an answer when asked a question, is to say "I don't know, I will get back to you" or to recommend someone else who will know the answer.