Cingular Wireless has credited 88,000 customers, mainly in Howard County, for $427,000 in mistaken charges for a new telephone tax imposed by Prince George's County, Howard consumer affairs administrator Stephen D. Hannan said.
"This turned out to be a lot more than I thought," Hannan said, recalling estimates he made in October that maybe 15,000 customers had been overcharged $4 to $5 each.
"We're asking Cingular Wireless customers to review their bills of the last two months to determine if they received a credit for the original erroneous charge," Hannan said in announcing the scope of the overcharges.
Cingular officials acknowledged their error almost immediately when customers began complaining in October. A handful of Verizon customers -- mainly a few who once lived in Prince George's County -- were also affected.
John Johnson, a spokesman for Verizon said "about eight" customers were charged mistakenly, including Dora J. Benedetti, a North Laurel real estate agent who still cannot understand how she got stuck with the 8 percent tax.
"They did take care of my refund," Benedetti said.
Bill Theiss, a Howard County Council employee, got credited for the charge after noticing it in October, but he never suspected how many other people were affected, he said.
"I was shocked it was so high," he said.
Hannan said many Cingular customers were hit with the charge because the company did not "do due diligence with their software" in making sure its computer billing distinguished between Prince George's County, where the new tax was enacted, and Howard next door, where there is no local telephone tax.
Baltimore City and Baltimore and Anne Arundel counties also have local telephone taxes.
The problem first came to light when a resident called Raymond S. Wacks, the county budget director, to complain about paying the nonexistent tax. Wacks referred the caller to Hannan's office, which conducted an inquiry.
The item was labeled "county tax" on the bills.
Kate Paxton, a spokeswoman for Cingular Wireless in Washington, was not available for comment yesterday.