If the bank does say fuck you, I'd file a complaint. If they still say fuck you, I'll reach out to the financial ombudsman service. And if they still say fuck you after that, I'll take them to small claims court.

What do you expect me to do? Investigate the matter myself? Buy myself an unlicensed firearm and look for the hacker to get it back at gunpoint?

In the multiple cases mentioned above the bank says not our problem and only reacted when it was on the front page of the daily telegraph

That's not exactly hacking, I've had a similar problem (paid rent by bank transfer and the "landlord" just vanished). The bank said "you transferred the money yourself, there's nothing we can do, it's like paying cash". Which is ridiculous, but technically it's not the bank's fault :/