You can also simply email them, referring the acknowledgement email you received and quoting the reference number provided therein
Checklist of what you will need
To prove that you have the right to make a request, you must provide one of the following documents: a copy of your Canadian passport or your permanent resident card, or an official document that demonstrates you are currently living in Canada (i.e. a driver's license, bill with proof of address, work/study/visitor permit, etc).
Only one (1) document is required. Your Social Insurance Number (SIN) will not be accepted.