Dell computer is continuing efforts to track down customers who may be using faulty laptop batteries and has asked them to dial a toll-free number to see if their batteries may be subject to recall. A spokesperson from Dell Computer's Beijing Office told Beijing Daily on Tuesday that most of the problem batteries probably entered China between last June and April. The batteries have been sold separately or together with Dell Inspiron 5000 series laptop computers, which cost about 17,000 yuan (about HK$15,640). Customers can also may find recall instructions at support.dell.com. The firm has said it would mail new batteries to customers and offer another free one when collecting the problem battery at a later date, the spokesperson told Beijing Daily.