it took almost 15-18 days in my case via webform. Actually after realising my mistake i tried to amend that. i wrote an email to the embassy where my file was supposed to be processed. upon that email they advised me to withdraw my file and re-apply. After that I wrote in webform that i made a mistake in the main visa file and i am taking the full responsibility of it. Thats why, i want to withdraw my file, so that i can re-apply with the proper file. they just sent me the confirmation email stating they received my query. after sending the webform within 20 days they updated my CIC account. and the status of my file changed from submitted to withdrawn.
Hope that helps.