BT's wholesale price to the resellers works out at about ?14, so you've got to figure that the cost of decent support and other overheads for the reseller has got to add another few quid onto that.
Frankly, anyone reselling broadband for less than about ?21-22 a month has slim to no chance of making any money at it, so if you're gonna sign up with what might be a 'fly-by-night' operation, get a short contract period and pay by credit card. That way, if the service is poor you can jump ship soonest, and if it all goes tits up you can get some money back from the credit card purchase insurance.
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