A "settlement processing error" caused Starbucks Corp. to double-bill customers' credit or debit card purchases at some of its coffee-shop locations on May 22 and 23, according to a spokesperson for the Seattle-based coffee retailer. "We resolved the problem, and customers should have seen resolution on their statements by" May 29, says the spokesperson. The representative would not confirm how many customers Starbucks charged twice or the name of its processor. Some media outlets, however, are reporting that Starbucks charged roughly 1 million credit and debit customers twice for their transactions. Starbucks in 2003 expanded its processing agreement with National Processing Co. to include transaction processing in Canada in addition to the United States. Bank of America Corp. in 2004 acquired the processor and changed the name to BA Merchant Services. In 2006, National Processing purchased back its brand from BofA along with more than 170,000 merchant contracts. A BofA representative declined to comment about clients and referred processing questions back to Starbucks. National Processing did not return calls for comment by CardLine deadline.