SEPTA said it is refunding Key card users who were charged double for trips on the rail system. The transit agency said it was caused by a "bug" in the software.
Riders may had noticed the duplicate fare charges in their Key card accounts, that, for some, resulted in a negative balance.
SEPTA said the issue with the software that caused some fare validators to go "off-line" had been fixed Wednesday.
Refunds had been issued to about half of the affected customers, SEPTA said, as they work to correct the remaining accounts by the end of the week.
Get top local stories in Philly delivered to you every morning. >Sign up for NBC Philadelphia's News Headlines newsletter.
The Key card is reloadable, contactless chip card launched by SEPTA in 2018. It can be customized with different fare options for travel on Transit and Regional Rail.
SEPTA said customers should contact Key Customer Service at 1-855-567-3782 with questions or concerns related to possible fare overcharges.