A LEADING Hong Kong insurer is planning to break brokers' stranglehold on car insurance by going direct to the public. Carlingford Insurance Group is believed to be starting an advertising campaign tomorrow urging those preparing to buy car insurance to wait until the official launch next week. It is also believed the company will base the service on Direct Line, Britain's leading motor insurer, which revolutionised the British market by offering cover over the phone to private car owners. The company would not comment on the move, but is known to be angry at the way other general insurance companies are flouting attempts at self-regulation by paying more than double the agreed commission rates to brokers. Carlingford is believed to have lost about $20 million in sales because it stuck to the agreed industry limit of 15 per cent commission. The company recently warned that it had no intention of being ''bled to death'' by competitors that were breaking the arrangement. The company is understood to consider that it can cash in on widespread dissatisfaction with brokers, who can collect up to 35 per cent of premiums in commission for selling a compulsory insurance to drivers. It is believed Carlingford considers it will be able to emulate Direct Line's experience of being able to offer car drivers lower premiums by cutting commission overheads and using a telephone pool rather than a network of branches or a direct sales force. Earlier this week, the company claimed that most of its competitors were paying more than the agreed commission rate. The 20-month agreement to limit agents' commission to 15 per cent of the premium was an attempt by the industry at self-regulation. It followed criticism of industry commission rates by the Consumer Council and calls for greater transparency. But many companies used it as an opportunity to outbid their rivals and buy market share by raising commission rates. Consumers appear to be reluctant to shop around for cheaper rates and it is likely that any attempt to introduce a telephone-based service would have to be accompanied by a major advertising campaign if there is to be any chance of replicating the dazzling success of Britain's Direct Line. In a separate move, the General Insurance Council is expected to have discussions with members over the next few months about ways of attempting to reactivate the system of self-regulation.