Hi everyone interested in biometrics payment!
I'm a Sponsor and is a representative of my husband.
Request to pay biometrics came to my email from
Centralized-Intake-Office@cic.gc.ca
In e-mail it was written: Ones completed, send the payment receipt via web form
https://secure.cic.gc.ca/enquiries-renseignements/canada-case-cas-eng.aspx
In web form, in applicant section enter your PA's data, Enquiry info - yours.
After you upload your receipt, you will be asked for email and date of birth confirmation.
In my case it was my email (as I'm a representative) and PA's date of birth
Good luck to all of us!