the seller has the control over him ( the buyer )
I wouldn't write in that way - filled with weak expression and rudimentary mistakes; instead, I will write it in this way : A buyer is a person whom the seller controls.
However, the sentence itself is ambiguous due to the idiomatic error. I would like TS to clarify the actual meaning of the sentence, or the intention of the sentence.
我个人觉得是,卖家可以控制买家