I recently had cause to thank the bank systems recently. Not for stopping a fraud but for stopping a thieving insurance company.
I always canx/don't agree to auto renewal on insurance.
Recently my son's car insurance was due renewal. We found a good deal with another company.
A few days later I got a text (at silly o'clock in the morning) from the bank asking if I recognised a transaction for around £850. The transaction had gone through about 03.30 in the morning.
I responded nope and had a reply straight away saying they'd blocked it and cancelled my card.
I went back to sleep and later in the day checked my online banking before ringing them. It was then I realised what had happened. Checked my records and confirmed I'd definitely cancelled the auto renewal the previous year when taking out the insurance.
Rang the bank and explained, no problem and they reinstated the card.
Upside was I didn't have to chase a refund from the insurance company and wait around ten days for it.