I have now spoken to the block booking person. She was very apologetic and admitted that she made the mistake. The other team should not have had their booking approved, as we should get priority given our long history of playing at Whittington Park.
She has promised me that our next booking (the game against Brewdog) will be honoured as agreed, and she will contact the other team to tell them their booking is off.
We will receive a full refund for our booking yesterday. Everyone who paid me will get a free game the next time they play.