Not sure that you can. If you sent it nearly two months ago that's likely within the unspecified grace period for sending to the wrong address after they changed it. Acknowledgement of receipt (AOR) takes a while, 6-8 weeks usually and it seems a bit longer for some of late so it sounds like maybe you're just in the final part of the wait for that. Sending to the wrong address would likely add a bit of time to the wait as well as who knows how they get it to NS, or how often they send stuff over there.
I'd wait another couple of weeks and then try phoning them, though if your application is just waiting for them to send AOR the problem is it won't be in the system so they won't be able to update you on it. And if they've sent it back I'm not sure if it makes it into the system either.
The number for IRCC is +1 613 944 4000.
