An official bug report in-game perhaps? People also use Twitter.
Sometimes people post a video of a bug they experience on Reddit. Although, be warned, as a mod on /r/runescape, you have to make your post detailed and the video clearly showing what the issue is or you risk it being removed. We're currently cracking down on posts people make for the the sake of farming karma. Basically, we're trying to do the opposite of what the /r/2007scape mods do. Or in this case, don't do.
#ShotsFired