Credit disappeared

I regularly order items from takealot, and I am very rarely disappointed. However I ordered a few items before my last 2 orders and one of the items did not arrive. So I was credited the money into my takealot wallet. However when I wanted to place my next order that money had disappeared and I had to pay the full price. I feel that it is not wrong for me to want my money back because I paid for an item I did not receive. I tried contacting them to resolve the issue, but I am unable to reach them.