Without some quota system on RM, there is no way to prevent this.
There needs to be a download limit of X amount of Kb or Mb per day per group.
I beg you guys to consider this. VB has download limits per group. The resource manager should also. When our site was on VB, I had 5 users come on, before I mastered the settings, and they literally burned through the metered bandwidth for an entire month in 2 weeks, and I had to pay for extra.