Rossei said:It's always safer to mail the requested docs when the LVO doesn't specify means of sending docs. However, you should make both soft and hard copies of all docs you send out in case you need to email them/upload onto MyCIC later. People whose LVO is London will be able to shed more light on this.
You, as a sponsor, can pay RPRF on your parents' behalf using CIC's online payment service with your credit/debit cards. You would however require an online account to use CIC's payment service. After payment, you will need to save and print the RPRF Receipt. Attach this page with all other requested docs (Receipt number normally looks like this: Rxxxxxxxxx).
Here is the link: https://eservices.cic.gc.ca/epay/order.do?category=8
Tahnk you so much Rossei.