Translation:Please help my younger brother.
Traditional Chinese: 請幫助我的弟弟. In simplified Chinese 帮, 邦 acts as an indicator of sound.
Both is fine. There are many phrases in Chinese that you will realise, may only need one of the two words to express the same meaning. Like 怎 in 怎么. It's just that in modern-day Chinese, the 2-word form of these phrases are more commonly used, while the 1-word form of these phrases almost automatically give it an 'ancient-style'. 帮 is however an exception where both are pretty modern-day. I would feel 帮 is the much more casual one of the two. I think 助 also adds to the tone.
Is 班助 used instead of 班because I'm asking for help on behalf of someone else?
I'm not a native Chinese speaker, but from what I've read, and from SeeMin3's comment above, 帮助 and 帮 mean the same thing. But I guess 帮 is more casual, while 帮助 has a slightly more formal tone.
How many times do I have to translate this same phrase? At least vary older/younger brother/sister each time!