Does the scratch affect the images? It takes a lot of damage to a lens to make a small difference to the image.
If it does, the "cheap and nasty" way to fix it is the fill in the scratch with black ink. Sounds bad, but it actually works. If light can't get to the scratch, it can't be diffracted, refracted or scattered into places you don't want it.
Perhaps a local repair shop or authorized Sony repair shop might be able to do things that Sony themselves aren't prepared to do, though of course if Sony won't sell individual lens elements, there's not a lot they can do.
It's impractical to repolish and recoat a lens and the results would probably not be as good as the original anyway.
If you take the camera apart every week and clean out the dust from the lens, you need a different camera. That lens isn't meant to be taken off the camera and I'm very surprised that it's possible to take it apart without damaging it at all (unless you're just removing a filter).
There are small dust and moisture sealed cameras that would be much more appropriate for your work. For example, the Pentax Optio W60 is fully sealed and can even be used underwater!
See Pentax Optio W60
~$330 at Amazon.com