https://vietnamembassy.ca/consular-services/criminal-check-police-certificate/
I got mine through them, you just need to download the forms (application form + credit card authorization form) - the form i filled was in Vnese tho so maybe you should switch it to Eng, or you just simply call them to request for an Eng ver, then send them back to
visa@vietnamembassy.ca
I was told it'll be ready and sent to my address within 15 business days.
Costed me $450 USD in total (that includes $35 USD Fedex)
Hope this helps!