NO INTERNET CONNECTION TO 3COM MODEM/ROUTER

Hi to All who can help,

Recently I have just bought a 3Com OfficeConnect ADSLWireless 54 Mbps 11g Firewall Router for my brother. He is on a 10Mbps Broadband Plan from SingTel. This is a 3 in one modem, router and wireless. I have bought this router based on the shopower's recommendation. Anyway this is the problem since day 1. The MIO modem that was provided by SingTel works fine with his internet connection except that wireless is weak and very unstable. Thats explains why I bought for him the new router. Somehow the 3Com router just could not detect any DSL connection at all . The Syn LED light which is the Internet LED on the MIO modem keeps on blincking. I have done everything that's to be done. I thought the set could be faulty so I brought it down to the shop. They tested and it work. So I thought it could be my configuration. I brought it back and the same problem persisted. Then I call the shop again. It was then realized that the DSL signal coming in from the telephone exchange was too weak. It seems that because my brother has extended his phone socket from 3 (original) to 5 points. Using the same cable and point, when I pluck into the MIO router (2WIRE), it works!!!!
It is very frustrating as nothing could be done other than sell the set away or rewired the whole telephone network. You see, my brother has lost the receipt, that forbids me to get even a refund or exchange.Could anybody help me please on this sickening problem. I can't use this 3com router as I am on cable.Is there anything I could do to boost or increase the DSL signal ? I have even called the SingTel technican and he claims it is not due to the singal. What can be done ? Is there a better microfilter on the market that could solve the problem. I am at my wits end. I fell like smashing the router !!!!. Please help. Thanks.