OK I found out what happened from a NY Times article.

Air America had paid for March, but did not actually use the time.

Meanwhile, during that period, the station's owner rented the time out to
another broadcaster and collected those amounts from the other broadcaster.

When Air America found out, they claimed that they should be credited with the
amount paid by the other broadcaster. In other words, that the owner should
have to account for revenue he received selling time that Air America had
already paid for.

I think they will be found to be correct on that......