I bought my bike there as well. I just checked, the site does say that specs can change without notice, but if that's the saddle you had in mind, it's a little different than changing brake levers. A lot more comfort related. Ask them to swap it out, you send yours, they send you the Cervelo. They should definitely do that. They are likely out of stock though, so you may have to wait.

But definitely call them to explain