When Austin Dillon checked his bank statement online Friday morning and found thousands of dollars missing from his account, he thought for a moment that he might be a victim of identity theft.

It only took a couple of scrolls for the 33-year-old Oxnard, Calif., man to realize where the missing money went: His trip to a Santa Paula Del Taco fast food restaurant cost him $4,260.

“On my actual receipt it said $4.26,” Dillon said. “I thought it was funny. I figured it would be an easy fix.”

A quick call to his bank and Dillon’s money was back in his account, but he soon found out that other affected customers weren’t so lucky. About 10 customers gathered at the restaurant Friday morning with complaints of being overcharged, and some had gone into negative balances after a technical error affecting ATM and credit card transactions tacked on thousands of dollars to bills.

“I had the money in my account,” Dillon said. “If it had been before Christmas it might have knocked me out of the water.”

About 150 people who ordered from the food chain were mistakenly charged, but a spokesman with Del Taco said all charges will be refunded.

"They were really cool about it," Dillon said. "They were super apologetic."

The Associated Press contributed to this report.