Well, if there is no alternative with a business cabin it's difficult to make amends.

I once had a downgrade to single cabin A320 on CCU DEL and was told to go pound sand by e-commerce@ai because it was just a leg in a bigger ticket. I just went to the airport a little early so I was in time for the previous flight which was a 787. After some debate they rebooked me in business to the earlier flight.