I have received an email saying I owe them money, ...

I have received an email saying I owe them money, followed by a convincing letter stating that the debt is from HMRC, however when calling them they seem to be fishing for more of your details to pass security to enable them to talk further.
I have contacted my accountant and she has double checked that I have no outstanding debt to pay and has warned me to ignore BPO collections and she will forward any further letters to HMRC Fraud department.

BETTER LUCK NEXT TIME BPO COLLECTIONS!