For ridding injustice and oppression of oppressors, one should say this du^a' in the person's face:
الله الله ربي لا أشرك به شيئاً، ربي اكفنيهم بما شئت انك عليهم قادر
Allahu Allahu Rabbi, La 'ushriku bihi Shay'a
Rabbi-Kfinihim Bima Shi-'ta Innaka ^Alayhim Qadir
Or:
Allahumma Kfinihim Bima Shi-'ta Innaka ^Alayhim Qadir
And this Ayah:
{وعنت الوجوه للحي القيوم وقد خاب من حمل ظلما}
Wa ^Anatil Wujoohu Lil Hayil-Qaiyoomi Wa Qad Khaba Man Hamala Dhulma
And this Ayah:
اِنِّىْ مَغْلُوْبٌ فَانْتَصِرْ
Inni maghlubun fan-tassir
As for needs, one should read Du^a' al-Hajjah to fulfill one's needs:
Pray 2 Rak^ah and Say the du^a' and in the end make whatever intention you wish.
(((اللّهم إني أسألك وأتوجّه إليك بنبيك محمد نبي الرحمة، يا محمد إني أتوجه بك إلى ربي في حاجتي لتقضى لي)))
which mean" O Allah, I ask You, and I direct myself to You in supplication by our Prophet Muhammad, the Prophet of Mercy. O Muhammad, I direct myself to Allah by you, so my need [here the specific need is mentioned] would be fulfilled.
Tabaraniy narrated that the Prophet taught this to a blind man, he went and did as the Prophet ordered. Shortly thereafter, he returned to the Prophet's session with his blindness cured
* But one must make sure the letters are pronounced correctly.
May Allah make things easy for us ameen.
Waffaqakumullah.
Remember, never forget to do your daily TAHSEEN (Protection Dhiker)
http://www.alsunna.org/Protection-Duaa-Tahseen-adeyah-aaltHssyn.html