Crashb4

Hi, I have the same problem other day I parked my car and as I start walking alarm go off and it's happend 2 times in day I don't know what to do. I have another question please anyone can help me I recently bought 2002 Camry sportivo v6 but the priviouse owner only gave me one key I don't have remote key so any one can tell me how and where I can get remote key in Sydney.