Upgrade but no handset for over 6 months

We had received a call from the Vodacom call center to upgrade our existing contract, which we did, however, 4 weeks later and no handset received, we called to follow up and was taken through the procedure again, now 6 months later and still no handset, we then called to cancel upgrade and cancel contract, received a reference number and to date we are still being billed the upgraded rate and the case has been closed on Vodacom side without being resolved...