Crew welfare should be the concern of the state/authority where the ship is either arrested or abandoned. The port involved would normally have a prior claim to the cost of their berth or supplied services, against the value of the vessel, and crew's living or repatriation costs could simply be added to this - but it would, I suspect, mean that a legal change might be essential.
However, in EC countries it shouldn't be too difficult to enforce this - from what posters have said, looks like one sufficiently strong-willed human rights lawyer could do the job, as crew's human rights sound as if they are being seriously infringed upon vessels detained. The crew members concerned shouldn't be treated this badly in civilised countries, and while the charitable organisations which do their best to help are to be much praised, the countries and ports in which they are abandoned should do much more.
If you know of, or hear of, similar cases in the UK or European countries, where charities have proved the only support or where they have been unable to assist, I'd very much like to do a story about this on Shipping TV, so please get in touch.