Got an email link from Medstar Health (in Maryland) to schedule my COVID vaccine. Made an appointment and immediately realized I picked the wrong location. Cancelled it. I cannot reschedule. Then I read the FAQ. FAQ say if you cancel, you are shit out of luck. F-you, Medstar.
Who knows, your cancellation could have been the most fortuitous day of your life.?.?
Maybe you can call them, and get a human to schedule. Explain that it was not a fickle cancelation on your part, but a flaw in the sign up process.