Thinking you know the answer, and knowing the answer, are two different things.
It is very easy to think that you know the answer, and then act on that information, with good intentions.
However, that can make things difficult later, because your action is based on misinformation.
It is more difficult right now to notice that you do not actually know the answer, and, however well-intentioned you may be, you still do not actually know the answer.
Once you have practiced noticing thus, the solution becomes obvious.
Learning the answer – and, in Customer Service, that means taking the extra step to ask – erases all future difficulties which may arise.