If you desperately want to leave your network but don't want to drop, e.g., €300 in one day for the privilege, you should be able to leave and continue paying o

If you desperately want to leave your network but don't want to drop, e.g., €300 in one day for the privilege, you should be able to leave and continue paying off the €50/month that you've signed up to and to do what you want with the handset.