So like Bla1ze already stated: install an OS that's not from Roger. If you follow the instructions you will be alright. It will not matter for your phone. It will function the same.
If you don't already have DM installed on your PC, do so. Make sure it's talking to the phone properly. Download .342 from cellcom wireless israel or telenor, install it on your PC. You can either manually remove the vendor files or use a tool like bbhtool to shrink the os and remove the vendor files. After that, start DM with your phone connected and it should do the update.