Solid Hardwood, Engineered and Laminate Flooring - New Hardwood Floor Uneven

I just had solid oak hardwood flooring installed in my family room. We've discovered that the floor is even. We didn't notice that the floor was uneven until we put our heavy oak coffee table in place. It is now a teeter-totter. The installer said he would check to be sure the floor was flat. I have talked to him and he says and he says he'll take a look but he's thinking no big deal. He was told that we had raised areas in the floor when we moved in. The builder came and sanded the floor joists, which helped, but we still had raised areas. We have this problem in most of our rooms, and I would like the floors fixed before we install any more hardwood. Can someone tell me what needs to be done, or should I have the floor removed and put carpet back on it? Do I need a contractor, or can a flooring installer fix this?
Just know you know, you can feel the rises in our floors through thick carpet.

Thank you,

Dave