So your customer is driving you crazy. They keep changing their mind, demanding quick responses, asking for the impossible. "It is difficult to do business with them" you say. Well, how easy is it to do business without them? Do you know why the phrase The Customer is Always Right exists? It is really quite simple. If you don't have customers - you don't have a business. Are they always right? No, but their opinion certainly does matter. In fact, their opinion is EVERYTHING.
I don't care how smart you are, how organized your business is, how much market research you have conducted. If you have upset customers, and you are not doing anything to alleviate their concerns, they are going to leave. As a consumer, I know that if I do not like a particular business or product, that I have other options. And believe me - I am not afraid to exercise that right: the right to spend my money somewhere else.
I think most of us in business are familiar with this scenario: The customer is asking for something we don't offer, or is unhappy with the features of an existing offering or product. And we know that what they want either isn't what they need, or isn't in line with our current business plans. There are a few ways this can go. Either you convince your customer that they actually need something different than what they asked for via the "I am the expert and I know what you need, so shut up and listen to me" method, or they convince you that they need what they need and that is all they are paying you to do.
So what really should be happening here? Unless you are being hired as a neutral third party, to give your opinion on a particular subject, think long and hard about how you are going to message "you don't need what you think you need". There is a right way and a wrong way. And for the record, most ways you can think of are wrong.
The key in business is to have a product people need, message it affectively, and treat your customer's well. If you have what people need, and they can understand what you have - then you will begin collecting customer's. If you treat them well and listen to them, they will stay. If you cease listening to their requests, their perceived needs and their concerns? They will take their money somewhere else.