clips on sony ax2000 mount as quicktime with avchd file that cannot be opened - Help!

I have tried iskysoft medie converter and aiseesoft AVCHD converter for Mac -- they cannot read the AVCHD file. I cannot get either program to load the file. I have conntected the camera to the mac with USB and dowloaded the file, but then it cannot be opened in ANY program. Smaller files have opened in Quicktime, but these have many multiple clips. Anyone know how to convert these?