You will want to call the IRS e-file Payment Services at 1-888-353-4537. They're available 24/7.
- Once the return has been accepted the information pertaining to the payment, such as the account information, payment date or amount cannot be changed.
- If changes are needed, the only option is to cancel the payment transaction and choose another.
- To inquire about or cancel a payment wait 7 to 10 days after the return was accepted before calling.
- Scheduled payments can be canceled up to 11:59 p.m. ET two business days before the scheduled payment date. The cancelation must be authorized by the taxpayer.
For more information, see here.