Angry, complaining customers are a part of every business. You can treat them in one of two ways: they can be the problem, or they can be an opportunity to change a bad situation into a great situation. Of course it would be easier to pass it on to someone else and just deal with people who like you, but eventually each of them will be that difficult customer as well. The reason for this is because your company is not perfect and neither are you. At some point you will mess something up, it is how you deal with the mess ups that will matter the most to your customers.
Angry customers are usually something covered in most sales training courses. Angry customers are almost always angry because they feel like they have been wronged in some way. The product didn’t arrive at the time they thought it would, they were charged more than expected, the new delivery person was rude to them, or something else equally as bad.
To use the last as an example: the truth is that it is completely true that the delivery man may have been rude because he was having a bad day and got into a fight with his wife that morning. Or maybe he thought he was being nice, but they just took it as being rude. No matter what the truth is, the customer doesn’t care about the reason they just want the problem fixed. There is a very simple solution to the problem too, take the delivery guy off that route and give the customer someone else as well as a bonus perk to show that you really care and are sorry that this happened.
The key point is to remember to not get upset with the customer, or baby them. Treat them with respect and caring. Show that as much as they care about your company, by letting you know that something went wrong and giving you a chance to fix the problem, you care enough to fix the problem and show them you are glad that they are one of your customers.