People who act on your recommendation sometimes come back to you with questions.
WHAT TO DO
For anything about their account, billing, or a technical problem, direct them to open a ticket from their Client Area. They are our customer and we can help them directly.
For general advice about their site, help if you want to. That is your relationship, not ours.
WHAT NOT TO DO
Do not present yourself as able to act on their account. You cannot, and implying otherwise creates confusion. Do not offer to contact us on their behalf about their account. We cannot discuss another customer's account with you, and it wastes everyone's time. Do not promise outcomes we have not offered.
IF YOU ARE ALSO THEIR DESIGNER
Ask them to add you as a contact on their Client Area account with appropriate permissions. You can then open tickets and reach cPanel legitimately, without sharing logins.
WHY THIS MATTERS
An affiliate referral makes them our customer directly. That is the difference from reseller hosting, where they would be yours. If you want the ongoing relationship, reseller is the model that provides it.