30 Megabit (Mb) = 3.75 Megabytes (MB), make sure you confirm with your ISP if they're counting in Megabits (normal) or Megabytes.
Still, there is some odd stuff going there. Your network is restricted by using WiFi, but it would only be that bad if your adapter was a true piece of stuff. Got a name for the hardware device you're sing to connect to WiFi?. Given that there's no processes consuming mass amounts, it looks like a hardware issue. Anything else in the home consuming bandwidth?