Likewise there is a lot of injustice in the world, today. I see poor people not paid fairly, refugees are denied justice and the greedy pervert justice. I see governments treating their citizens badly, decisions are based on expediency, and those without a voice are disadvantaged.
However in the book of Habakkuk I find two lessons. One is that Habakkuk didn't fix the problem. He went to God. Secondly God said he would fix the problem but not in the way Habakkuk wanted.
I cannot fix all the injustices I see but I can go to God. I am not called to fix every problem, meet every need or carry every burden. However I am called to fulfil the ministry God has given me and I am called to play my part even if my part seems small and insignificant – a few prayers, a donation, sign a petition, buy fair trade products. I can't do everything but I can do something and the little things are important.
Furthermore I can trust that God will fix injustice on his terms, according to his timetable and not mine. God told Habakkuk that he was going to use the Babylonians to discipline his people. This seems rather strange as the Babylonians were more wicked than the Israelites. Nevertheless God involved a pagan nation because he had a long term plan in mind. Often we look for quick fixes whereas God has the eternal in mind.
God loves justice and will bring it about in his time.