Friend..
Complain his true embodiment of dissatisfaction, not willingly accept a provision that occurs, both in terms of material and non-material.
Friend..
Allah Almighty loves a servant who is always grateful with all the provisions and be patient when overwritten something that is not in accordance with the wishes.
"And if ye count the favors of Allah, ye can not determine the number" (Qs An-Nahl 18).
When a person is swept away in a complaint, his or her five senses can no longer play his or her role to see, hear, smell and feel the blessing that is spread by Allah unceasingly.
His heart is blindly recalled and grateful for the infinite blessings of Allah. That is the human nature that always has an unlimited and insatiable desire for God's gift except grateful servants
Instead, complain is only to Allah SWT, because actually all events have become a provision of Him and only God is the best solution-giver.