IRS removed my payment.

[xing-du]

So I owe IRS money this year, and I paid via IRS direct pay through the official website. The payment was listed on Apr 6th, and the amount was deducted from the bank account on Apr 7. However, I got another notice on Apr 26, telling me that “we removed a payment applied to your account in error.” I feel very confused about it. I will call IRS again to figure out why but I would like to know if anyone has been through similar cases?

[DawnC]

Was the notice on 04/26 from the IRS?   Did it come in the mail?   And have to checked your bank account to see if the payment was reversed and credited back to you?  

[xing-du]

The notice was dated 04/26, available in my IRS account online as well as mailed notices in the paper.

The money returned hasn't shown up in my bank account. I understand that it might take some time to have the balance reflected in the account, but I just want to make sure it will eventually be adjusted and my second attempt won't fail like the first one for no reason. 
I have tried to IRS today but no one is available to answer my question.

[DawnC]

It is probably just a timing issue.  Going to link here to another discussion where the user explains how to get a live rep on the phone at the IRS if you want to try again later.  

[xing-du]

I followed that instruction. Unfortunately, at the last step, it just hangs up instead of sending me to a waiting line. 

[xing-du]

Some interesting follow-up on this. 

I tried another number (from this website: https://www.irs.gov/help/contact-my-local-office-in-california) which is basically a line to make an appointment for a local office in-person visit. Somehow I got transferred to an IRS staff. He double-checked my account and told me that my current balance is 0 and I can ignore that notice which was probably generated before my payment was confirmed (although my payment is listed on Apr 6, 2021, and the CP 60 was dated Apr 26, 2021). I am very confused about the information system IRS used.