I does not have any experience in unlocking mobiles with software because i am using only codes to unlock mobile phones..........codes are the easy and the safe way to unlock mobiles.......
Good place to get a unlock code for your sony ericsson w300i model mobile here Mobile Unlock Solutions , it gives easy ways to get your mobile as unlocked........
Hi free software tools some times won't work. So better you can go for paid unlocking service. I would suggest this site ClassicUnlocking.com here you can get the unlock code and unlock your mobile. To get the code you have to mentioned which country is locked now,network provider and imei number. Then they send unlock code through email.