You might occasionally hear that said in a joking way, with roughly the meaning you intend, but it's not proper English, no. You'd ask to have something specific fixed, like writing, as in your example.
Seriously talking about "fixing someone" is usually offensive, as it implies that something is so deeply wrong with them that they're "broken" or less than human.
Answer from the-baby-is-you on Stack ExchangeYou might occasionally hear that said in a joking way, with roughly the meaning you intend, but it's not proper English, no. You'd ask to have something specific fixed, like writing, as in your example.
Seriously talking about "fixing someone" is usually offensive, as it implies that something is so deeply wrong with them that they're "broken" or less than human.
It is grammatical, and people do say it sometimes, but it sounds very blunt and harsh. "Fixing someone" implies that that person is "broken," which would generally be considered an insult.