+1(514) 937-9445 or Toll-free (Canada & US) +1 (888) 947-9445
What is the difference between this webform:
https://www.canada.ca/en/immigration-refugees-citizenship/corporate/contact-ircc/web-form.html
and this one
https://secure.cic.gc.ca/enquiries-renseignements/canada-case-cas-eng.aspx

I need to let IRCC know of change of residential address for both sponsor and PA.

I recommend to use the first link..I used a different link before when we submitted the reply for a PFL and they did not received it..Then, I resubmitted it using the first link that you posted and they finally got our submissions..