I got a message said that my Auto-Payment was returned

On this Monday, I received a message from AT&T that I have made a successful Prepaid payment. However, today, I received a message that Your recent e-check payment was returned for insufficient funds. Please call 866.853.2574 for more details. My bank account has sufficient funds and I guessed that I maybe filled a wrong bank information, maybe routing number or else. I wanted to check my Auto-Pay Payment at AT&T website, but it showed that "Error! You have order in collection. No payment can be made until it is resolved". So, I cannot change and check my Auto-Pay Payment  information. What should I do now? The phone number 866.853.2574 is reliable?

Thanks