A study conducted late last year is evidence that broadband customers should dig beneath the surface when mulling over deals.
That it is the advice handed out by Moneysupermarket, which has highlighted its own survey which revealed 4.5million households have been hit by hidden charges totalling £160 million.
According to the price comparison website, the data should prompt prospective broadband contract holders to take a closer look at the packages on offer to them.
"As long as you have a rough idea about the speed you need and whether or not you can put up with a download cap then comparing products is easy," said Moneysupermarket.
Before firing the warning: "The reality however, suggests we need to look a little deeper when comparing products or we could be in for a nasty surprise."
It was found that BT customers paid the most in stealth charges, recording a £51 average.