CHICAGO (CBS) — Rachel Heiress isn’t trying to park her Millennium Falcon, just a small sedan at this week’s Star Wars Celebration fan convention at McCormick Place, but she now has reason to worry her prepaid parking passes might be worthless.

Heiress has been a Star Wars fan since she was a kid.

“R2-D2 is my favorite,” she said. “I’ve liked R2-D2 since I was a little kid.”

Naturally, with the out of this world fan convention, Star Wars Celebration, headed to McCormick Place this week, she paid $250 for a 5-day pass, and $72 for two days of guaranteed on-site parking at Lot A.

“This is Star Wars Celebration. I expect it to be huge, which is why I bought the parking pass,” she said.

The C2E2 comic book convention, with similar crowds, was held at McCormick Place last month and Heiress began reading online reports about overflowing parking lots, and passes McCormick Place couldn’t honor.

“It was actually on C2E2’s official Facebook page,” she said.

The notices about parking at C2E2 stated Lots A and B were at capacity. Prepaying fans were sent elsewhere, left to complain about having to pay again to park at a different lot.

“Not being able to get in with my prepaid pass, that bothers me,” she said.

Heiress reached out to McCormick Place parking lots for clarity, but got no response. Now she’s worried she’ll have to arrive six hours in advance to guarantee her spot.

“If I don’t get through, I could miss some of the event. The panels start at 11 a.m.,” she said.

If you’re headed to Star Wars Celebration, the ParkMobile app, which sells parking for McCormick Place, has promised a refund for anyone unable to park with a prepaid voucher.

SP+ Parking, which operates the garages at McCormick Place, questioned the validity of the online complaints, insisting staff accepted reservations from drivers who inadvertently ended up at the wrong lot.

Vince Gerasole