In English you complain “about” someone, not “from” someone. By the way, technically, the correct sentence in English is WHOM do you want to complain about, not “who.” That’s because the verb “complain” takes an object and in this sentence the object is “who” , and in the objective case who becomes whom. But, I admit millions of native speakers make this mistake all the time because English speakers are sloppy and lazy speakers as it is.

The correct sentence is: What do you want to complain about? (If we mean 'a thing') or Whom do you want to complain about? (If we mean a person) I hope it helps. :)

''About" is correct. "From" would have almost the opposite meaning: "The company received several complaints *from* angry customers. The customers complained *to* the company's public-relations department. They complained *about* the company's exploding phones."