Trev,
The bank is correct. There is no longer a requirement for a signed mandate - it is all done electronically between companies and banks. Banks now accept a direct debt instruction at face value when a company set one up with them. However, the existence of the direct debit indemnity scheme entitles you to a full refund if a mistake is made. There can be no claims of negligence against the bank. If you are sure the direct debit is not yours, insist on your IMMEDIATE refund!!!!!
Dianne (ex-banker)