Le and Lo

[Bobbert]

I have trouble trying to figure out whether to use LE or LO when talking on the phone in a formal/semi-formal office setting where I volunteer. Even though I hear other volunteers who are mostly second generation Mexican-Americans using TÚ and TE for EVERYTHING, I try to shy away from doing the same in order to make the office sound more professional and to show respect to the caller.

When I look for the answer using Google Translate or other sources, they also tend to just use TÚ and TE for all of their examples, so that doesn’t help, so I now turn to the grammar experts on this forum.

With that said, I am confused as to whether to use LE or LO for the following and the reason why:

I’ll have her call you.
I usually say: Haré que (ella) lo llame,
but I have no idea why I choose LO; it’s just a guess that sounds right to me.

I’ll have him call you back.
I usually say: Haré que le vuelva a llamar,
but I have no idea why I choose LE; it’s just a guess that sounds right to me.

I’ll have him return your call.
Haré que le devuelva la llamada,
but I have no idea why I choose LE; it’s just a guess that sounds right to me.

I’ll tell her to call you.
Le diré que lo llame; it’s just a guess that sounds right to me.

As you can see, I sometimes use LE and other times LO and I'm just guessing, but I don’t want to guess and use what sounds right to me anymore, so please shed some light on this. It will be greatly appreciated.

Angelica wrote a very detailed thread awhile back covering direct and indirect objects, so along with that and the answer to this, I will be well on my way.

The people calling in are usually from Mexico along with a few Central Americans.