Bully tactics break deal and leave bad taste

I have just got of the phone with a pushy sale's person. It felt like a Rottweiler had me by the jaw. Between the first contact and the supervisor, the call went on for more than half an hour. I said I wanted to see the offer in writing. Of course, you only get this once you agree to the offer and hand over your bank details. I said I was not going to give them my bank details until I saw the offer in black and white. At this point, we parted ways. I felt exhausted after 30 minutes of haranguing me into agreeing to a change of insurer deal. You should be ashamed.