VODACOM NO Service

about every month my phone gets disconnect because Vodacom cannot pick up a payment,I phone Vodacom all the time speak to someone different each time,send hundreds of emails no feedback not on air??? just get cut off and then I cannot get anyone to resolve my problem?? who do I speak to????I have 3 contracts with Vodacom for a long time have been a customer for more than 18 years and this is the service and loyality I get??