Having just been subjected to it myself I am disgusted at this legally dubious and morally repugnant selling technique. BT, listen up. I have been with BT for some time and until you did this I was basically pleased with the service I have received from you and happy to continue. Now I feel bullied, shabbily treated and ripped off - in one phone call you've managed to destroy my customer loyalty. You may have retained some disgruntled customers in the short term, but many of them (including me) will remember the way they have been treated in this instance and will be off when the time is right. It's not just about price. It's about good customer care and customer relationships . You've just ruined this one.
If you're within a couple of days of "renewing" the contract, get back in touch with BT customer services, ask to speak to the duty supervisor (make sure that you get their name), and lodge a formal dispute, and demand that they review the recording of the original call (which can take a week or so).
BT caved in after a week, we do not know if on reviewing the call, their rep didn't state that there was no cooling off period, or if there was no recording available.
Needless to say, we are no longer with BT.
Best thing to do with all this BT nonsense is to complain to Trading Standards and Ofcom, and consider sueing BT for compensation in the small claims, maybe then they will get their act together.