As a Koodo monthly customer, how do I switch to the Canada-US plan (from Canada-only plan)?

I want to switch to this Canada-US plan from my existing Canada-only monthly plan: 
“K2T Unlimited 100 5G+ - Unlimited Canada-US talk, text and 100GB data at 5G+ speed up to 2Gbps”

However, I cannot find the plan on the Koodo self-serve page while logged in.  How do I switch to the US-Canada plan from within my Koodo account?

I understand Koodo is part of Telus so presumably it should be simple to switch between plans within the same company?  I want to keep the same phone number (important), account, plan add-ons, etc.  The only change is switching to the Canada-US plan (for calling, texting and mobile internet).

I learned about the offer from promotional email directly from Koodo to the email associated with my account, addressed to the account holder: 
“Switch to a TELUS CAN-US Unlimited rate plan and get 100GB for $75/month Plus, we'll waive the connection fee when you activate online.”