What you come up with is polite enough. Another option is something along the lines of,
I hope to move forward on this project next week. Please send the requested documentation by Friday; if that is not possible, please let me know when I can expect to receive the documentation.
It's a little more pointed but gives a deadline (useful) while acknowledging that their timescale may not be the same as yours (polite).
I assume by "Sorry to bug you again about this" that you were already given help with "X", so instead of an apology, perhaps a thank you would work better:
Thank you for your help with X, but we are still having problems with it and...
This is most likely how I would write it, an apology seems to be an admission that you feel "bad" for asking and can sound "whiny", while a thank you gives the idea that you feel "good" about their previous help and appreciate it.
If you are paying for this service or for support (which you may not be), I wouldn't worry about apologizing for requesting it, especially if your previous request was not attended to.
I would like to use examples of the two sentences above in an email directed to an organization, but I would like to avoid using "you" or "bug", if possible.
I don't think it's quite necessary to avoid these two words, but there are a number of options if this is your goal. For example:
- Sorry to be a bother...
- Sorry to burden your staff with this... (still uses a form of "you")
- I/We apologize for the repeated request...
Personally, in any case I would drop the apology or thank you, in fact all extraneous parts of the email altogether. Busy people like to get things done quickly, and if their staff has a lot of work they'll appreciate a to-the-point email. However, it depends, and I recognize that this viewpoint avoids the literal question of what to replace those two words with.
Best Answer
You could say: