I want to use my Xperia S for debugging, so I followed the OEM USB Drivers instructions step by step but still not work, I didn\'t find "Android Composite ADB Interface
I had terrible problems with my Xperia U and dis-ability of my PC (even the PC companion software) to see it. I tried many solutions posted on the web, nothing worked.
Finally I just switched the microUSB cable to another one I had and suddenly it works. I even uninstalled PC companion and other Sony bloatware and it is still working!
So not sure what that original microUSB cable is for (I bought my Xperia U as a second hand stuff, so not sure if in original package there are more micro USB cables), but for me it worked just for charging of the phone, no file transfer.