A GROUP of investors in now bankrupt Lehman Brothers in Hong Kong yesterday demanded a full refund of the money they lost, dismissing a settlement offer as “unfair.”Hong Kong regulators announced Sunday that banks which sold minibonds linked to Lehman had agreed to repay investors up to 96.5 percent of their investment. But the proposal was criticized by the Allied Victims of Lehman Products, a pressure group that reportedly represents about 7,000 Hong Kong minibond holders.