Cao Zaixue was on top of the world when he landed a coveted civil service job as a mining researcher in Liaoning province . But six months later, Mr Cao was in the depths of despair after losing his job - and began digging for the truth behind his unexpected sacking. He chipped away at the corruption that had cost him his position, filing petition letters and visiting petition offices - and eventually struck gold. A year after being sacked he was reinstated, apparently on the order of Premier Wen Jiabao . Mr Cao's ordeal began in July 2003, when he secured a job with Fuxin's Bureau of Planning and Resources after graduating from Liaoning Technical University with a master's degree in mining. It took six months before he was paid for the first time - 2,400 yuan, or a monthly salary of 400 yuan. 'They said 400 yuan a month was a good deal for me because I didn't have any personnel connections,' said Mr Cao, adding a civil servant of his rank should have been paid 900 yuan. He said that shortly after joining, bureau party chief Liu Tiejun threatened to sack him because he had not paid to get his position. 'He summoned me to his office and said 'everyone has paid 30,000 to 50,000 yuan to get a job in the bureau. I'll kick you out because of how you got in',' the 29-year-old Sichuan native said. Mr Cao was fired in January last year and told 'there was no quota' for him. 'They hired two more staffers after me. How could they say there was no quota for me?' He then embarked on a year-long quest that reached the highest levels of government. After eight fruitless visits to the provincial petition office, Mr Cao joined the thousands of petitioners who travel to Beijing to air their grievances. His petition reached the State Council - and the ears of the premier. Mr Cao said he was told Mr Wen had intervened in his case. Mr Cao was informed of his reinstatement in December but still has not been told when he can start work. 'I'm glad it's over now. I've been through a lot of pressure and desperation in the past year,' he said. Mr Liu has denied Mr Cao's claims but refuses to elaborate on reasons for his sacking.