usability – How to prevent users from bypassing a form?

I have a multi-step form that starts with a question. If the user says No, he is directed to a screen asking him to call back (since the system can not process any response). If users respond with Yes, they go to the next step of the form.

The problem is that many users, after selecting No and seeing that they have to call, will simply go back to the question and say Yes to switch to the form.

This creates a lot of problems at the end of the day since we can not serve any clients (therefore, we should redirect them, etc.), which creates a high cost of service.

There is no way for us to distinguish Yes vs. No users before they access the form.

What solutions can mitigate this problem?

enter the description of the image here