"Sitesauce hosts your static sites on Vercel (formerly ZEIT), offering unlimited bandwidth and their world-class CDN for no additional cost."
Then in your Terms of Service you say:
"You agree that Sitesauce is not responsible for any additional fees charged to your credit card by third-party server providers such as Vercel."
How does the hosting work? Do I sign up with Sitesauce and also sign up for Vercel? If that is the case, would I be able to pick a different host if I wanted? If it isn't the case and Sitesauce handles the backend process of creating an account on Vercel is it paid for by using my credit card and you pass that info to Vercel?