Whoopsadaisy! Citigroup has accidentally been charging many customers more than what they owe for months, with some of them not even realizing it was going on until the bank sent out a notification. Cit’s bill-pay app for iPads was the culprit in many cases, charging customers twice what they owed for bills or mortgage payments.

The New York Times says the bug started in the iPad app around July but wasn’t detected until December, after consumers’ complaints about payments being off. Other mobile applications and the online bill payment system weren’t affected, says Citi.

However, some customers who never even used an iPad to pay bill said they’d also been hit by double charges, something that hasn’t been explained away yet. The bank is promising to reimburse customers and waive any fees incurred because of the extra charges, as well as give out a few points for its reward program.

“We take seriously the functionality of our products and services as well as the satisfaction of our clients,” spokesman Andrew Brent said in a statement.

Users of Citibank Bill-Pay App Charged Twice [New York Times]

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