I couldn't get through to anyone at the IRS either. I had my bank cancel the extra payment, which started an entire nightmare. My erroneous double payment and then having my bank cancel one of them a day afterward started a terrible chain reaction that I'm still dealing with. The double payment caused the IRS to auto issue a refund check unbeknownst to me. I'd already had my bank cancel one of the payments as I said, so I looked up to see what to do when you get a refund you should not have gotten. It said to return it to the check to the IRS following a few steps--and I did so. That was over two months ago, I think. The IRS STILL hasn't credited my refund check back to my account even though my certified envelope was received two months ago. Now my account still says I owe money and I don't and there is no one answering phones at the IRS.
Long story short. Do nothing. The IRS should send you a refund check for the extra amount, just do not cancel your accidentali extra payment as I did.
If you must contact someone about it, which I finally did, they'll tell you just to wait it out as you/we shouldn't get any penalties because they go by the date they actually received the erroneous check or payment. I got through to the IRS Tax Advocate line at [phone number removed], which isn't the IRS, but they can look up things on your account for you.
