A two-year freeze on rents was today demanded by the Green party’s London mayoral candidate as she said urgent action was needed to tackle “out of control” housing costs.Zoe Garbett, who will challenge Labour mayor Sadiq Khan on May 2, said “skyrocketing rents” in the private sector meant key workers were unable to live in London.She published a “renters’ charter” that seeks to establish a “rent commission for London” that would set a target level for rent and aim to reduce housing costs.It would also increase pressure on the Government to grant the mayor powers to control rents. At present there are no restrictions on how much landlords can charge.