betray by friend

After go kampar for studying, dont know what happen to all my friends. Some become nicer, some become mature but some become worst. No matter how a friend become also wont betray own friend but i have one friend that betray us causing us into trouble. Starting with my this friend is a cell phone owner, he trying to sell a phone to my "sis" but he want deposit first that is around (RM400). After he get the money, he didt give the product on time and starting delay the time. He will say he got accident unable to give or get rob by robbery. But is it really happen within one month accident three time and got rob by four time? i also dont know.... Starting we all though is true but after sometime one of my friend start suspect him. Because he bring his phone for repair to my this friend(phone shop owner) but in a unlucky time saw he trying to sell his phone to other customer. So he start to investigate this person and found that he recommend one plan to us that we ady using got problem. Cause that plan no need to register but he request our ic to register but now we dont know what he done to our ic and use it in what purpose. We totally dont know and start found that this cellphone owner have own many people money and that is not a small amount all add together already reach 10k. At the same time, he also own me 400 i also dont know what happen and i feel nervous so i try to take back from him. But he also start delay my debt and everytime i call him his phone is unable to reach or off already so i also suspect this friend(cellphone owner). After two week that i request him to pay my money, he finally give me cheque but good thing not always happen that is a bounces cheuque. So this time it is already reach my patient limit, i call all his debter and go to his house to collect from his mother. No matter gangster or what we use all the forces that we have and try to take back our money. This time i only get back half of the money another half still try to take back. Well success or not still dont know have to wait but at least he want to face all the debters is already "cham". I also dont want to do this but he is forcing me and try my patient. Since i try to take back already waste one and half month so finally i do this decision since he dare to give bounces cheuque that mean he not longer take me as friend he already start betray us and use our identity to do other things. I dont want to say out only. I just want let other people know is no matter your friend how close with u in business world only can trust when give money and product at the same time and trust each other in coorperate not giving deposit. Dont ever give deposit that is very dangerous. Well now what can i do is use all my forceses to force him pay back why a friend that u know for 7 years also can change in suddenly and betray u.....