This happened to me about 20 years ago, on a flight from SA to Heathrow. We stopped in France, to refuel and the French would not honour the account, on account of Air Zimbabwe having a bad credit record. The pilot was more or less begging for immediate financial short term assistance.
After a few hours one of the passengers (who must have had a large credit limit) put the whole bill on his credit card. He was ushered off the plane first, to rounds of applause, and was greeted by people from Air Zim. I am fairly sure that he got his money back.