I get 10 spam calls from vodafone a day after more than 2 months of registering for full DND. These calls are in machine voices about some ringtone or something and there is simply no way to communicate my frustration at them. I realized customer is powerless to stop these calls and complaining anywhere will not help.
Hence I have decoded to use MNP to rid myself of these calls. Hope they do not bother me on another network.