You can also try using a different browser to see if it resolves the issue if not please see suggestion below.
If this issue is not resolved, please contact our Phone Support, they can take a payment over the phone and walk you through continuing to e-file.
If using Windows 10, please see TurboTax FAQ below.
TurboTax FAQ - What is the TurboTax phone number?
Why am I unable to continue to payment in TurboTax on Windows 10