Six million Britons are overspending on their broadband connection, according to broadband comparison site BroadbandChoices.co.uk.
More than half of all users could save up to £10 each monthly by switching to a different provider, the study suggested.
Just over half the people questioned said they didn't use the full monthly download limit they paid for.
The survey showed many customers were spending more than they needed to in order to stay on the safe side.
Several people said they were worried their broadband provider would restrict their download speed if they used more memory than their prescribed limit.
Nevertheless, "many of us have very simple online habits, such as a bit of online shopping and banking", remarked Michael Phillips, BroadbandChoices.co.uk's product director.
For these customers, the company recommends 'light user packages' with 1GB to 3GB download limits such as PlusNet Option 1, Eclipse Option 1, or Tesco Broadband's Value package.
But those customers who do use their download limits may be better off monitoring how much they use, and perhaps using up their spare capacity at the end of the month by downloading a couple of extra mp3 tracks or a TV show.
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