Yeah I agree that the fare rules probably did state that each sector should be used, otherwise the subsequent ones would be autocanx.
However when checking in at MSP the agent there really ought to have known about that sorta thing and pointed it out to the customer there and then, especially as they had been informed that the previous sector had not been used.
How do they expect to keep customers when they can't even point out when the rules have been broken?
cheers
FF