These customer dis-service desks are rubbish nowadays. Absolute rubbish and it's not only airlines that are rubbish, though they do tend to be rather good at it.
Anyway, there is a reasonably good chance that your PNR was passed to your credit card company as part of the settlement process. So you could try them.
I suppose the nuclear option is to charge it back on the basis that the airline has taken your money but will not tell you why.