First Timer

Recently had a very unpleasant scam call experience.  Callers knew my Account number and had all my details including Bank Details.  They said my router was about to fail and it would take 3/4 days to get a new one to me, unless they let me try and fix it.  Yeah, I know naive, but as I work from home, this was a very worrying and unwanted scenario.  Fortunately, my Bank phoned me to say they had noticed suspicious activity on my account.  No harm was done and all credit to the Bank's security measures.  What worries me, is these scammers still have all my details.  Why wasn't I alerted by Talk Talk.  When we tried to tell Talk Talk about this scam, they wouldn't talk to us about it, as they wanted details about our account, which they already have!! Quite frankly I want out of Talk Talk as I have no confidence in their security measures.