we'll get back to you
or
we will contact you
Mantenerse en contacto con nosotros. If you mean it as command i.e. "Stay in touch with us" as opposed to He wants to stay in touch with us", the Spanish command is "Mantente/Manténgase/Manténganse en contacto con nosotros" (tú/Ud./Uds)
Translation: Tiene Ud. alguien angloparlante con Ud.?
with= con with me= conmigo with you=contigo (for informal) or consigo (for Ud.)
As written, this is "The pleasure that you talk with you too". Perhaps "Es un placer hablar con Ud. también" would be better - "It is a pleasure to talk to you too.".
Formal: ?Puedo unir con Ud.? Informal: ?Puedo unir contigo?
"Me gusta estar con Ud. también, pero vamos a ver cuanto tiempo dura" - I like being with you too, but let's see how long it lasts.
Translation: Siento responderte / responderle con tanto retraso.(use responderte for a "tú" person or responderle for an "Ud." person)
Ya he hablado con ella. (I have talked with her already) Or...Ya hablé con ella. (I talked with her already.)
Translation: Estoy triste cuando no estoy contigo. You could also say "Me entristezco cuando no estoy contigo" (I sadden when I am not with you), but this is more literary, although the emotion comes off more strongly. Just as a note to your translation: "con tú" does not exist in Spanish and always becomes "contigo". (The same with "con mí" becoming "conmigo". "Consigo" has a set of unique rules which is why "con él", "con ella", and "con Ud." do not automatically become "consigo".)
UD Maracena was created in 1945.
UD Alcúdia was created in 1975.
UD Salamanca was created in 1923.