I submitted the request via Webform to withdraw my sister's application which by mistake was submitted for Visitor visa instead of Study permit ( not sure how) but its been more than 1 month and still active.
2 weeks ago, we did get the reply for IRCC stating that they have forwarded the request to the admin to withdraw the app and refund the fee but no update since then.
Regardless, last week we have submitted the new application for Study permit.
In short, it could take some time.