I will explain the scenario first.
"I was trying to talk to my friend for many days. But he was busy with his own works. Then he messaged me that he would call me the next day for sure. But he didn't call me even the next day."
I have a complaint with him for not calling.
But I am thinking that the word "complaint" is kind of a formal word. I would like to know about some casual word for it.
I tried Googling and found the synonyms quarrel, disagreement, gripe etc..
But we can't use those words in a casual way.
What are some thoughts on this? :)