One million UK consumers have exceeded or come close to exceeding their broadband usage limit, research from consumer group uSwitch has found.
So-called usage caps, where internet service providers limit the amount of bandwidth users can have in any given month, are standard practice.
But the majority of users are still confused by the bandwidth curbs imposed on them, the research found.
For some who go over their limit the penalty is disconnection.
"With so much reliance on broadband, having the service disconnected could feel to someone as serious as having their electricity cut off," said Tim Wolfenden, spokesman for uSwitch.