I have had the same problem - no response from Air Canada after writing twice about missing miles for a LHR to YYZ sector on AC metal in May this year. I sent copies of the boarding pass and e ticket to the AC Elite address in Montreal in early June and again early August. So far no points credited and no response.
The web site states 4-6 weeks for missing points to be credited. It would be great if AC could at least respond within this time frame, confirming receipt and explaining that due to 'abnormally high workload' processing times would be extended.