Design: My Job or the Client's?

Hello all,
I have a problem. I have a customer who has agreed to a design that I created, and then signed my contract. Then he decides he wants to change the design. Now, I already have a good vision for where the current design is going and that it is most likely to succeed with the audience the client is aiming for.
The client, as mentioned agreed on the previous design after many changes and I have already spent the amount of time allocated in the contract for design. The changes he wants will ruin the whole atmosphere of the current design and will not target the audience he needs. I met with him today and he asked for all these changes and I gave him my reasoning for why those changes would not work. I even offered to make the changes to demo it for him.

Then I come home and I get the following message:

One other item is that I have a vision of what I want and I know you have a vision as well. It will be much easier if you will simply make the changes I recommend. I really believe this goes back to listening to the customer and I hope it helps your business in the future.

and then he gave me a whole bunch of changes.

Well my question is, he is completely right about listening to the customer, but I have listened to him throughout the whole process and we have come up with the design that he liked (a LOT actually) but now he has changed his mind AGAIN.

From my experience with past clients/work, whenever a non design person has sat behind me while I designed, the designs have been largely unsuccessful and a waste of time for me and the customer, and now he is asking me to do just that.

So who is really in charge of design?
Me or Him?
– he has a vision, it is his business, should he be in total control?
– I have a job, and its to make his business successful by making a good design by using my expertise and experience :h: