Hmmm, I'm not sure. I think Scarborough is the closest office to your location so it could be Scarborough.
If you've received a test invitation, you can find the abbreviation for the office in the email ID. For example, SCR = Scarborough and MIS = Mississauga. You can also find this information in the GCMS notes.
If you decide to call them again, you should ask a leading question like "Could you please tell me what my local office is?". You can also raise a webform request and ask which local office your application is being processed.
Good luck!