Before you get offended thinking people are blowing you off, realize that many of the mods and the webmaster are still on active duty so they deploy or go TAD on a regular basis. As such, whoever you sent a PM to might not have access to the site to answer your question.
For regular users, after a certain amount of time, you lose the ability to edit your posts. I don't know what that time frame is, I guess I need to find out. If you need something edited, post it here and one of us will "fix the glitch" for you. Another option is to report your post and in the reason for reporting it, just ask to have it changed to read whatever.