Re: "the respondent purporting to be a TalkTalk representative hung up"
Talking to 'Jo', a supervisor, on another matter I mentioned having received a number of such calls. She immediately gave me the 'speil' about such calls. Having worked in the field myself (which she didn't know) she said everything which I would have advised.
For those whose phones show the caller's number it will appear to be a UK one but there is no such exchange code. I then did a 1471 and got the caller's number (abroad with an unlisted country code close to but not that that for Bermuda). Having got that number I simply googled it and it was listed as a scammer working not only Talktalk but also PPI and a few others.
Jo told me that Talktalk wants all those those numbers.