It is sometimes difficult to define the problem and sort out real differences. The first, most important step, however, it to determine that the customer complaint is fully understood.
5W2H :
Who? Identity customers complaining
What? Identity the problem adequately and accurately
When? Timing - When did the problem start?
Where? Location - Where is it occurring?
Why? Identify known explanations
How? In what mode or situation did the problem occur?
How Many? Magnitude - Quantify the problem
To reduce the risk of making wrong decisions, consideration and analysis of potential problems in advance will provide contingency actions to maintain control and protect the customer.
. 
