Translation:¿Por qué ellos no te visitan?
why can't I use "se"? Por qué ellos no se visitan. What is wrong with that?
To say "you," you want the direct object pronoun: te (for tú), lo/la (for usted), or los/las (for ustedes).
"Se" changes the meaning of the sentence to something along the lines of "why don't they visit each other, or themselves, or why aren't they visited?"
I am quite unsure about using the phrases a ellos, a usted, a el and the likes. I tried to say "por que no te visitan a ellos" (don't mind the accents). I would like to know the reason this is wrong and the rules for using a ellos etc.