I said to her “If you let your son do whatever he wants, you will spoil him.”

I said if she lets her son do whatever he wants, she will spoil him.

I warned her that if she let her son do whatever he wanted, she would spoil him.

I warned her that if she let her son do whatever she wanted, she would spoil him.

I told her if her son did whatever she wanted, she would spoil him.