Please consider getting some documentation in writing in addition to your LoE. People who have been successful have submitted emails from the Canadian Embassy in Korea, Korean Consulate in Toronto, and Korean National Police as supporting documents. Here are the email addresses so you can get those:I am having the same difficulties getting the police certificate. I went to the embassy in London to get the police certificate with lapsed records and they said that they are not allowed to issue this certificate as this is only possible to obtain from within Korea and even then it's only for personal use so it may be difficult to obtain. So they will issue just the "Background Check (Criminal Records) Certificate".... I will submit this with a LoE explaining the situation and hopefully, the application will go through smoothly.
toronto@mofa.go.kr - Korean consulate in Toronto
seoul-cs@international.gc.ca - Canadian Embassy in Korea
crc@police.go.kr - Korean National Police