Won't honour credit

Our booking was in credit due to Covid. They advised that we have to use it by December 2021. Asked for mid week at Mabalingwe 4th - 8th October. They advised its peak season and my credit didn't cover the booking. Offered to pay in, in order to get booking. Advised that Mabalingwe was at full capacity!! Never heard of such *******... Clearly just want to bank my credit.