Vodacom service useless

This problem is ongoing for more than a year now...its ****!! Vodacom makes promises to fix it...but never does!! Signal is on and off the whole time...can't hear the other person.... its time time change contracts to MTN. Atleast they provide a service! Having a slogan of Power to You doesnt make sense if you can't call!! Fed up. Wonder what promises vodacom will make this time....