In the small print for BT basic broadband customers, there's something quite alarming - it says that consumers can be slapped with a 33% rise in price after one year.
At the moment, the standard package for BT is being advertised for £13 a month. However, on July 3rd, that will go up to £15. Then, in the t&cs, after one year, the price will go up again, to £20 per month.
Of course, there's a monthly charge of £18.99 for line rental to add on top of all this, and it all starts adding up.
So, if you sign up for that, you'll be paying £38.99 per month, for broadband that is 'basic'.
Of course, headline grabbing introductory offers which end up being rather expensive, are nothing new. Companies know that, with the addition of exit fees, or the plain hassle of having to switch accounts, a lot of customers will just put up with what they've signed-up for.
EE are another - they have offered deals for £1 per month, but again hidden in the small print, the price rises to £9.95, along with a £17.50 monthly line rental fee.
Sky have even offered free broadband, but after 12 months, it goes up to £10 per month.
That's exactly why we're warning you about such things.
There's cheaper deals to be found elsewhere, clearly. Depending on your needs, you could for example, go with Vodafone's basic broadband deal, where you pay an average of £21.16 per month.
SSE also have a 12 month broadband deal, which gives you line-rental and broadband for £21.49 a month.
The Advertising Standards Authority are currently looking into this, but it looks like there'll be no meaningful changes until new regulations come into play on October 31st.
A spokesperson for the ASA said: "It is important that advertisers are completely transparent about their costs so consumers aren't misled. This includes making it easy for consumers to see all the costs of their product."
"We are aware this is currently not happening as often as it should. That's why we have made the change to how these packages can be advertised."