Never got a confirmation email for my repair

What should I do if I never got a confirmation email for a computer I dropped off at the Genius Bar for repair?

I dropped off my MBP at the Apple Store three days ago.

Instead of getting a paper receipt my genius told me I would be getting a lot of emails keeping me up-to-date on the progress of my repair.

I am very concerned because I never got any confirmation email from apple. I tried looking up my repairs with my apple ID and got "Apple could not locate any repairs". I also tried looking up repairs with the case ID from the genius bar appointment for the drop-off: nothing except the details I entered when I made the appointment.

Adding to my concern is that my genius was helping several other people at the same time as he was packing up my MBP for repair.

Apple's support options all require me to enter the serial number. I stupidly did not write down my serial # and now apple has my computer.

I tried to call support but there are unusually long wait times. I will have to try again later.