this is what cic call centre emailed to me hope it helps
Sir, Madam,
Thank you for contacting Citizenship and Immigration Canada. I am pleased to follow up on your request:
Right of Permanent Residence Fee (RPRF) Payment Receipt - CPC Mississauga
If you have already paid the $490 Right of Permanent Residence Fee (RPRF), you must send a copy of the official receipt to the Case Processing Centre (CPC) in Mississauga, Ontario, by email.
You can also send a copy of your official receipt by mail/fax. Please find below the contact information for the CPC:
General Mailing address
CPC Mississauga
P.O. Box 6100, Station A
Mississauga, ON
L5A 4H4
Courier Address
CPC Mississauga
2 Robert Speck Parkway,
Suite 1200
Mississauga, ON
L4Z 1H8
Fax: (905) 803-7392
Your email/letter must include the following information:
• The sponsor's name, date of birth and address;
• Your client ID, UCI or application number (if you have one); and
• The type of application (e.g. sponsorship of my spouse).