Well technically I have just left (hence me feeling comfortable to share my day to day job) as I am starting a new job in a new field!
I am not sure if I feel comfortable to say which bank still, but I used to work as a senior call centre employee and investigator in the fraud department of a main high street bank and used to work in the main call centre role before then (logging the fraud and day to day banking queries). I still spoke to customers on the phone after becoming an investigator, just not as much as before.
I will try to answer as many questions as possible if I get any. I dealt with customers who are fraudsters and those who have been scammed/frauded. I have left now to work in a completely different field for much better pay after accepting a job so can happily talk about this one.