In one incident, the bill was for $5.48, but the customer's account was debited for $5,480.
Customer Michael Cole said he was surprised when he was charged $4,050 for one CrunchTada Pizza and two beef tacos. He discovered the error Friday when he tried to withdraw $20 from an ATM and was denied.
Del Taco says it was a technical glitch by a third party card processor, and refunds were being issued.
The glitch affected about 150 customers who used ATM and credit cards at the Santa Paula Del Taco location Monday and Tuesday.
Del Taco issued the following statement: "Due to a recent technical issue, various Del Taco customers at the Santa Paula, Calif., restaurant were subject to erroneous charges on their ATM and credit card accounts over the course of a 24-hour period. The credit card processor is aware of the situation, and has contacted the individual banks involved in an effort to reverse the charges as soon as possible. In fact many customers have already seen charge reversals on their accounts."
The Associated Press contributed to this report.