I agree with those who suggest that you should be able to complete your initial training (first 20 hours or so) with only one instructor, changing only if it your choice. If you think instructors are trying to not fly with you, better ask yourself (or them) why?
However, consider that though the instructor may be there to "instruct", and some of that will be necessary for you to learn, the instructor is also there more simply as a qualified person who will assure your safety, while you learn yourself. In my opinion (I'm not an instructor), after 8 hours of training, the instructor should be able to sit back and watch you fly, with only minor pointers and observations. Intervention should not be required, other than for intense maneuvering, and close to the ground. If this is not so, they are not relaxed with you flying. You need to sell them on your skills - whatever they are!
Are you mentally prepared to learn to the greatest extent while you are flying? Getting in the plane, and telling the person beside you "teach me to fly", is really the hard way for you to learn. After a few lessons, your interest should be so peaked that you enter the cockpit with a hundred questions each time, something new you want to experiment with, and new elements you would like to explore for those things you have already learned.
My opinion is that generally, if the instructor sees that you have a gentle touch, and respond promptly and well to verbal instruction, it should be possible to talk you through most of the flying, without his/her touching the controls much at all. To satisfy myself of this years ago, I mentored my 15 year old cousin for only her second ever flight in a light aircraft. After 1.6 hours of getting her relaxed and confident with the controls, I had talked her through 2 very adequate takeoffs and landings on a long frozen lake (so runway dimension was not a factor). I did the power, but she did everything else on her own. She had not expected the flight that day, but was certainly very enthusiastic, and primed to learn.
Prime yourself to learn in every way you can. Probably sitting in the aircraft for a half an hour or so before each lesson will help. Think of it this way, you're paying to be there, every moment that your are not actually flying the aircraft, you're missing the best value of the flight. If the instructor takes the controls, do whatever you can to make him/her confident that they do not need to be in control of the aircraft, you will do it at least adequately.
Let us know how you make out...