There are two isssues here.
If the OP was negligent with his pin, then he has no claim in my opinion and should not be compensated. The bank has to investigate this. If he has used the card in an atm where there has been a scam, he will be compensated.
The bank should have cancelled the card, but a chip and pin card is relatively safe and not cancelling it, is not the issue here. I would guess that far more is defrauded through people who are careless about their pin than through organized fraud.
The bank has to investigate it. It's not a time for ranting and raving. It's a time for putting out the facts and determining if the OP was negligent or not.
If the bank denies liability, then he can take the case to the Financial Services Ombudsman.