The IRS accepted my return which included the used Ev tax credit but they have since amended my return so that it no longer includes the credit. What can I do next?

Did they say why they disallowed the credit?

They did not as it was in the Where's my refund app. I assume it will be included in the letter they are sending me or they said I could call the IRS which I'm going to do after work. 

You'll want to wait and see what the letter says.