US Visa renewal by mail / interviews waiver

Hi there,
We have applied with DS-160 form for renewal of US Non immigration visa B1/B2 recently.
And the visa fee was paid, too. We can apply for Visa Renewal by mail as all criteria is met in our cases.
During online filing we are not offered interview waiver option. So with confusing whether we need to get appointment or not, we could only book an appointment after 2 years. Note: while we booked appointment there was system maintenance. Though we received Yatri: U.S. DoS Visa Application Confirmation.
But on visa status check, we get- Your search did not return any data.
And we can not reschedule the appointment time as in Toronto -There are no available appointments at the selected location.
Now please help me -
**How can we enter in interview waiver program i.e. Visa renewal by mail **? What are the steps?
Is there any web portal regarding this issue?
Any help is highly appreciated.
Thank you.