Is Linking to a Contact Form a Web Accessible Solution for a Live Chat Button?

I have a website that has a "Contact Us" button that opens a live chat window. It looks like this:

This particular live chat provider is not accessible to those with disabilities. We contacted them and they said they're going to work on it eventually, but not anytime soon.

Rather than switch live chat providers, I was thinking of providing some alternative to those with disabilities. For example, a link to our contact us page, which has a contact form that is accessible.

To be clear, this alternative would be in addition to the existing live chat button. So those who do not have disabilities could use the live chat, while those with disabilities would use the contact form.

If it matters, we're aiming for WCAG 2.0 AA compliance.

If you were making this live chat accessible, what would you do?