Two constituencies in Devon are among the worst places in the UK for broadband - according to the latest figures.
Nearly half of internet connections in Central Devon and Torridge and West Devon fail to reach the Government's proposed minimum standard.
A cross-party group of 57 MPs have backed calls for automatic compensation for families who don't get the internet speeds they pay for.
The British Infrastructure Group of MPs report found as many as 6.7 million UK broadband connections may not be receiving download speeds above the proposed minimum download speeds of 10 M b/s.
An Ofcom spokesman said: "We share concerns that broadband must improve, and we're already taking firm, wide-ranging action to protect customers - including new plans for automatic compensation, faster repairs and installations, and ensuring providers commit to giving accurate speed information to customers."