New H1B stamping - Dropbox from Canada


Had submitted documents for dropbox processing in Canada for new H1B stamping. However, the status shows refused and interview required. The question I have is - in such cases, will the consular officer call us to attend the interview on a particular date given by them or should I book an appointment myself?

Has anyone faced this issue and have they received any letter or anything when the documents were returned (I’m yet to receive my docs)?
Also, the available dates for appointment are only in September/October 2023 in Toronto and I only see Toronto as an option in the consular section drop down menu. How to get other locations visible/to select appointments other than Toronto. What options I have?

Appreciate any suggestions/responses. Thank you!