folks i would assume he means 1200MB(~1.2GB)/month, for a year.
and to the OP,I send, third, fourth, whatever, get a wireless router and set up wifi @ home ASAP.
My nephew is in a similar situation, but he's only got 120MB tripled to 360MB... which is NOTHING. Luckily, I'd set them up with wifi at home a couple years back, and his School has an open network.(K-12 in one building, all the students from 7th grade & up Get School Supplied Laptops.)
This One (Currently $24.99 @ Amazon), was up on Meh.com recently for $12. Not the greatest, but fairly decent, and super easy to set up.
The "Doofus" in that video is Matthew, the Meh.com "Video Ombudsman". His Job is to Make a new video for Meh several times a week. (was daily for their first year, but now every couple days), He's one of the many Meh staffers who used to work for Woot.com(where he did the same thing) until shortly after Amazon Bought & Ruined Woot.
Check out their YT Channel here:
https://www.youtube.com/channel/UCUughwYY6tc45culJCYsDcQ