HP says it will consider lengthen the free after sale service to its customers in China. [CFP]

Zhang first journeyed to an "official HP service center" in Zhongguancun last week to be told he would need to pay 2,000 yuan to change his graphics card. He ignored the suggestion and located the genuine service center, which then replaced the part for free on Monday.

In the same shopping mall, some shops were promising customers they would keep repair fees as low as possible.

"There is no difference between us and the official service centers," said a shopkeeper who refused to reveal his name.

"If your laptop has passed its guarantee period, you will need to find the cheapest price possible," he said.

"Laptops that have been repaired or had parts changed by unauthorized shops will not be refunded or replaced," a male service employee of the authorized HP service center told METRO. "However, we will still apply to HP for the repair of affected laptops, even if they were repaired in unauthorized shops," he added.

Isaiah Cheung, global vice-president of HP, said last week that HP would provide maintenance service or recall problematic HP computers, based on the "Three Guarantees" of repair, replacement, and refunds for substandard products.

On Friday, China's top quality watchdog, the General Administration of Quality Supervision, Inspection and Quarantine, announced that HP had violated China's consumer rights regulations.