Disappointed in Vodacom , bad service

I've been waiting for two weeks for Vodacom to cancel one of my contracts to upgrade on my other account. I've phoned them more then 5 times already and every time they have the same excuse that there system is slow and will phone me back, not one of the consultants phoned my ever since!! Two of the consultants told me that they will escalate the matter and management has to get back to me within 48 hours, its been three days!!!! I'm so disappointed as i have been a customer for more then 9 years and this is the service I get.