You can get the unlock code for a SONY ERICSSON W550i from www.prounlocking.com/sony-ericsson-w550i/rs8wp9/
at affordable cost.
Here are the steps for unlocking a Sony Ericsson W550i,
1 - Switch ON your Sony Ericsson W550i without
any SIM Card,
2 - Press the left arrow
3 - Press the button * twice
4 - Press the left arrow
5 - The message "Personalize with MNC2" will appear, (or you will have
displayed an unlock menu, select the lock you want to unlock)
6 - Enter the Unlock Code.