India, June 18 -- A northern Colorado airport shuttle service suddenly shut down, leaving customers with ride vouchers they can't use and no clear answers about when-or if-they'll get their money back.

Eight Black Airport Shuttle announced on its website and Facebook page that it officially closed on Friday, June 13. The message, signed by owner and founder Simon Chen, left many customers frustrated and confused.

"I sincerely apologize for not including information about how we would handle vouchers in our previous email regarding the closure of our shuttle business. That was an incredibly difficult day for me professionally," the statement reads.

"We are actively working on a system to manage the refund process, and it is my full inte...