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What happens if the decision hasn't been made past the expiry of the WP-Ext letter? Will the ircc send another letter to continue working until the decision is made?

Just read the letter, says pretty much that you can keep working till you hear from them.
 
when you submit a webform to update your address, do you get an acknowledgement of receipt, like an email or something? I didn't receive any acknowledgement after submitting one