[gTen]

IT kinda depends on your state law..the federal law only prohibits cloning..but you are not the one who did the cloning..so it does not effect you but what does effect you is once you know a device has been cloned it is illegal to use it. With the exception that the manufacturer can change the ESN...I think it also extends to the carrier so they may be able to fix it as well if they offer repair services.

Now as for fixing it yourself, it depends on your state law..Some just disallow cloning only, but don't address repairing the esn. Others forbid touching the ESN altogether.

If you have no options above, your choice would be to take it to the police and have them fix it.