A number of SEPTA Regional Rail riders have been double-charged on their Key cards for trips to Center City due to a bug in the transportation agency’s software, writes Lizzy McLellan Ravitch for Billy Penn.

The riders noticed the duplicate charges only after logging into their online accounts and reviewing trip histories. Those who submitted fare disputes with SEPTA have so far received mixed results.

“I was told there was nothing wrong on repeated occasions, only to find out later a duplicate charge had been applied,” said one of the affected riders.

According to SEPTA, around 1,600 customers were affected.

“The issue of duplicate fare charges on SEPTA customer Key cards was triggered by a bug in the software, causing some fare validators to go off-line,” said spokesperson John Golden. “The result was that some accounts incurred a negative card balance.”

SEPTA has already implemented a software fix and has started issuing refunds.

About half of affected Regional Rail riders have received their funds back. Those with weekly or monthly passes are receiving refunds automatically, while the remaining customers are expected to be refunded by the end of next week.

Read more about this SEPTA glitch in Billy Penn.