My Xperia z1 is shows as a z3!

Ages ago I was doing some stuff with flashtool on my Xperia z1 and in flashtool and my pc it shows as z3.. My model number shows as D6603. I want to get back to my old firmware which was 4.4.4 and my model number was c9603. I want to be on lollipop but cannot update OTA or using pc Companion as I get an error (2003). I downloaded a stock firmware of Sony Xperia z1 c9603 and tried flashing using flashtool but just stays on "preparing files" if anyone can help me get back to z1 firmware then please help me:) also I know it's a z1 I have as I brought it brand new. Thanks