What happened to my credit?

Yesterday morning my available credit on my TFG Money account was around R2000, however when I attempted to purchase an item online on Bash, it refused and said that I did not have any funds on my account, so I went on to check my available credit and found that it was R0. How this happened I do not know. I have called customer service, and they could not help me. like seriously TFG?!?!