Customized message on 'No slot available' page

Hello, @Mrinalini Jeedigunta! Unfortunately it is not currently possible to customize the page that appears when a link is no longer valid within Calendly. That said, we do have some other features you might be interested in! While they won’t resolve this issue, based on your desire for customization, they could prove useful in other areas of your workflow and use case!

1. Calendly Routing forms let you request information such as industry, company size, specific interests, etc. from website visitors and automatically direct them to a specific scheduling or web page based on their responses. It's great for screening and qualifying sales leads on a website or matching clients or students to the booking page of the right subject-matter expert based on their interests, program, or other criteria. You can read more about setting up routing forms, here!
2. Our redirect feature allows you to send invitees to a custom webpage after booking with you. You can also choose to pass information in the URL when redirecting. Read more, here and here!
3. You can embed your booking page on your website - and customize it as you go! Check out this handy overview of our embed options! You can also take a look at this website for examples of each one.

I know this isn't exactly what you wanted to hear but do hope the information helps, at least somewhat!