They are just so disturbed by something that your company has offered or hasn’t offered when they wanted it.Never hide any problems and never re-direct the mistakes to your fellow people.Understand the customers problems clearly.Don’t talk and try to convince them that it wasn’t a mistake on their part.Instead,try to convince them in saying that their problem will be sorted out ASAP.Tell them the actual time that you may require to get the job done perfectly.Don’t ask for more.You may irritate him again.Don’t ask for less.You may end up not doing it on time.So, you will have to think about the time frame that you would actually need to fix the problem and it has to be somewhere in between the two levels that i mentioned earlier.Following these easy tips may well help you reducing the number of customers who complaint against you.In fact, people would like you and try to befriend you so as to get the job done.Having said that all, it is also important that after the conversation is over, you take efforts to and do what you promised in time and report it back to the customer.This is the most important part of it.