There should be an email address to contact within your "Ready for Visa Email". See extract below.
"The processing of your application for permanent residence in Canada is almost complete. You must complete the following steps
within 30 days in order for our office to issue your Confirmation of Permanent Residence and, if applicable, your permanent residence visa. If for any reason you are not able to meet this deadline, please inform
CPC-Ottawa immediately by email to:
LDNIMMIGRATION@international.gc.ca with details concerning your situation."