Keep the contact link in one consistent place
G220 says that if help is offered anywhere in a set of pages, it appears in the same relative place on all of them. It is the only sufficient technique W3C documents for 3.2.6 Consistent Help at Level A. That rule has no advisory techniques and no failures. Four kinds of help count, and any one satisfies it. Human contact details. A mechanism for reaching a human, a self-help option, or a fully automated one such as a chatbot. One condition saves a lot of false findings. Consistency is required within the same size viewport, so a responsive layout that moves the contact link between breakpoints does not fail on that account. W3C also permits help that sits directly on some pages and inside a disclosure widget on others, in the same relative order, while noting that this is less consistent and less preferable.
How we find it in an audit
Our reviewers list where help appears on every template, then compare the relative order rather than the pixel position. Checkout and account flows are where it usually vanishes. Those templates were built separately. We hold the viewport size constant while comparing, since changing it mid-audit produces findings the rule does not support.
How affected users experience it
Somebody who has learned that help is the last item in the main navigation can go straight to it on any page, which for a screen reader user is a real saving. When it moves to the footer on product pages and disappears in checkout, that knowledge stops being useful exactly where they most need it. Readers with cognitive disabilities rely on the same learned position, and checkout is where the pressure is highest.
Passes vs. fails
Passes
Every template, checkout included, shows 'Contact us' as the final item of the main navigation.
Fails
'Contact us' appears in the top navigation on the home page, in the footer on product pages, and nowhere at all during checkout.
This guide is our interpretation of W3C technique G220: Provide a contact-us link in a consistent location. W3C publishes its techniques as guidance rather than as the standard, and says so on every one of them. The success criterion is what conformance is measured against, and a technique is one documented way to meet it.