I was going to call you yesterday, but I got very busy at home when I got back from work.Te iba a llamar ayer, pero me puse muy ocupado en casa cuando regresé del trabajo.
You didn't call me yesterday. - Yes, I'm sorry. I was going to call you, but I thought you were busy.No me llamó ayer. – Sí, lo siento. Lo iba a llamar, pero pensé que estaba ocupado.