AT&t is warning users about potential unanticipated charges on its prepaid plans after discovering they could be higher than expected.

In a letter to customers, AT&s wireless chief said the company is “looking into” potential issues with new AT &T prepaid plan charges and suggested that customers should contact the company for assistance.

AT&ts spokeswoman Stephanie Groszek said that AT&.s prepaid plan pricing is not designed to be a “discount” but instead an offer that gives customers the choice to buy a different plan with AT&t, the carrier said.

She said that while AT&tts prepaid plans are “not designed to compete with other carriers” they are “designed to be affordable and to be available in all markets.”

She said the carrier is looking into whether or not the issue has been identified or whether the issue affects customers who purchase AT&gtains prepaid plans through other carriers.AT&t said it is “working with the consumer to identify the cause of this issue” and is “actively working to resolve this issue.”

The carrier said customers should call its toll-free number at 1-877-872-5222 for information.ATs prepaid rates are based on an exchange rate that is used to determine whether the plan offers a higher or lower rate than what you would pay at a typical cellular phone.

The carrier has said it expects the exchange rate to increase and that it has worked to lower the rate for the current prepaid plan.

Groszek also said that customers with an AT&ltd credit card will not be charged an additional charge on their new prepaid plan if they have the AT&rt prepaid plan at the same time they purchase an AT &ltd phone.