有错误,用of which中间不能用and,
可以改成:An old acquaintance called him, saying that there was a recruitment of an assistant, of which the wage was high.
你的意思是要表达 一位熟人告诉他,说新来的助理工资很高是不是?是的话那语病有误了,可以这样表达,An acquaintance told him that a recruitment of an assistant who had a high wages.