On 22/11/2014 23:44, Tim Watts wrote:
They seemed more prepared and told me to ring the number on the back of
my card, then quote a reference they gave me.

Within 2 mins I was talking about the matter they wished to discuss.

Apparently that can also be part of the scam:
- The caller doesn't drop the call, but detects that you have tried to do so
- then plays a dial tone down the line to make you think the line call
has cleared down
- you dial the number from the back of the card, which does nothing
- a different scammer voice answers with a convincing patter and
continues to get you to hand over your security details...

I'm not suggesting you were scammed, just that it's been known to
happen. The recommended avoidance tactic is either to use a different
phone connection (i.e. mobile vs land line) or simply to wait for 5
minutes or so before calling back, which should mean the original line
connection will have timed out.