This indeed is a slippery slope. My final thought is that the charter companies should fully honor your contracted deal for a period of time without additional change fees. I’d say that 12-24 months would be reasonable. Cruise ship companies are totally refunding. Airlines are giving 12-20 months to use booked flights without change fees. If one argues about cancellation insurance and feels sorry for the charter companies well just remember that the charter company should certainly carry business interruption insurance. This is a big interruption.