I am in dire need of help because I can no longer use any version of Studio whatsoever after I had the unfortunate idea of launching the SR3 version.

After "installing" the SR3 package, meaning the latest one SDLTradosStudio2015_SR3_5262R.exe, I could not launch anymore Studio. I tried then to uninstall it and return to SR2. Studio 2015 disappeared altogether in all versions but:

1) If I try to reinstall SR2 I get this error message: "Set up did not complete. The error is: Set up has detected a higher version if this product already installed. If you still wish to install this version, you must remove the older version first".

In my Control Panel, I only have an "SDL Trados 2015 SR3 - Remove suite of products" but when I try to run it I get this error message: "Set up did not complete. The error is: Attempted to perform an unauthorized operation".

2) If I then try to reinstall SR3 I get this error message: "Set up did not complete. The error is: Attempted to perform an unauthorized operation".

In short: I apparently cannot fully uninstall SR3 to be able to at least reinstall SR2.

Please advise how to actually fully remove SR3. At least.