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.
The "just in case" part of your question is written from your perspective. You want them to contact you "just in case". There is no need to risk confusing the person to whom you are communicating by addressing issues from your viewpoint. Instead, write in the language and world-view of the people to whom you are communicating.
Please have xyz contact me next week, to address any unresolved issues I may have.
Best Answer
Here's a definition from Joel Spolsky:
So you can write, "We are users as well as developers of our own product; it's a reliable part of our daily workflow," or however it is you use it.