Thank you Corina_33 and Vaughan for responses,
I guess I didn't explain the situation very well, let me clarify some points:
1. Yes, I know AChat is free and we don't need a subscription, but I paid to buy A$.
2. I have checked my A$ balance and recent transactions, but nothing has changed.
3. There was also no response from the support team.
Something went wrong with the payment and the transaction was declined, after which I contacted CCBIll support and they approved the transaction. They also provided me with an “Order ID” and told me that I needed to activate my purchase by contacting AChat support and giving them an “order ID”, which I did.
And so far there has been no response from them, although they only had to make sure that my payment was correct (find the payment document by “Order ID” and check the status) and transfer A$ to my account.