File a support Case on Google Admin

Sometimes the issue is at Google's level.
In this case here is how you can file a support ticket:

2 Click on "File a support case".

3 Click on "Cases: Create a case"

If the issue is related to an account not seen by us when updating the signature here is a text sample:

We are using Google's API to update our email signatures. We can't update the signature for email xxx@sss.com