Why did I get a text saying you have canceled my prepaid autopay?

My original plan is $50, it can pay $40 per month with autopay.  I paid yesterday and my transaction is already completed. But, my plan is not working, and I have an ATT account balance for $5. Also, I got a text like you have canceled your prepaid autopay. What does it mean? Does it mean like can I get back $43.31 my bank account? I am really confused about what does happen. I don't know what plan am i using and what is the meaning of the canceled prepaid autopay. Can you check and solve for me?