Alko Lock drum won't turn

Jumbojetjockey

Hi. Please help anyone. My Alko Lock drum is "stuck." I can insert the key into the drum but in trying to unlock the barrel the drum seems to be seized onto the barrel but turns freely. I've put in WD-40, heated it up and clouted it but not too hard yet
and still the drum turns with the barrel. Any thoughts please. I suppose an angle grinder is the next bet. Thanks folks.

Jeremy.